Anatomy and physiology

A 77-year-old man with no significant medical history presented to the orthopaedic clinic of a metropolitan hospital with longstanding left mechanical knee pain. Examination and x-ray revealed features consistent with degenerative arthritis (Figure, A), and he subsequently underwent total knee arthroplasty. During surgery, a bluish-black pigmentation of the bone and the cartilage of the knee joint was noted (Figure, B). The patient’s surgery and recovery were uneventful. It was later discovered that he had a previously undiagnosed rare metabolic disorder, alkaptonuria, which affects one in 250 000 to 1 000 000 people worldwide.1 Alkaptonuria was one of the first inborn errors of metabolism to be described, in 1908.2 It is caused by mutations in the homogentisate 1,2-dioxygenase (HGD) gene, which results in a deficiency of HGD, which catabolises homogentisic acid (HGA). This leads to accumulation and deposition of HGA in cartilaginous tissues, causing a bluish-black discolouration (ochronosis).3 Ochronosis is generally asymptomatic, but ochronotic arthropathy due to deposition of pigments in the joints is common.3 The patient also had the characteristic ochronotic discolouration in the sclera (Figure, C), ear cartilage, fingernails and buccal mucosa, but did not report dark urine. The gene defect was not further investigated because of his age and excellent premorbid health status.

See-Seong Chang · Eugene T Ek · Vicki Pliatsios

Patients with schizophrenia have a wide range of risk factors for cardiometabolic disease, at rates 1.5–5 times greater than the general population. Despite the provision of many sets of guidelines and protocols for screening and monitoring of cardiometabolic risks, morbidity and mortality rates for those with psychotic illnesses remain excessive and premature. Surveys of mental health practitioners reveal a clear acknowledgement of the importance of managing cardiometabolic risks and subsequent comorbidity. However, inadequate screening rates of patients with antipsychotic-treated mental illnesses suggest “knowing is not doing”. Surmountable barriers (at service, patient and illness levels) to adequate integrated health care are not being adequately challenged for this population. Recommendations to improve the situation include service reorganisation, communication enhancement, improved training and education, better incentives, accreditation rigour, and government leadership.

Tim J R Lambert MB BS, PhD, FRANZCP · John W Newcomer MD

The estimated glomerular filtration rate (eGFR) algorithm has some advantages over serum creatinine concentration for estimating GFR. There are a number of caveats around the use of eGFR, predominantly because it assumes subjects are of average body size and similar lean body weight. eGFR has not been validated as a safe method of adjusting drug dosing, nor as a screening test for impaired renal function in the general population. eGFR has not been validated as a robust measure of kidney function in many groups (eg, older people, inpatients, differing racial groups, obese people). eGFR is inaccurate in many settings, such as in high, low or rapidly changing GFRs. Until evidence of safety and efficacy is provided, eGFR should not be used for calculating drug doses, and use of the Cockcroft–Gault formula or other validated methods should continue.

Jennifer H Martin MB ChB, FRACP, PhD · Michael F Fay MB ChB, FRACP, FRACR · Jacobus P Ungerer MB ChB, MMed, FRCPA

Estimated glomerular filtration rate (eGFR) using the Modification of Diet in Renal Disease formula has been shown to provide unbiased and acceptably accurate estimates of measured GFR across a broad range of individuals with impaired kidney function. eGFR is superior to measuring serum creatinine (SCr) concentration alone, more accurate than other prediction formulas (such as Cockcroft–Gault) in the setting of reduced kidney function, and more practical and reliable under most circumstances than measuring urinary creatinine clearance. Routine eGFR reporting with requests for SCr, in concert with clinician education, has been shown to enhance the detection of chronic kidney disease (CKD), resulting in improved cardiac and renal outcomes for patients. eGFR has been shown to effectively identify individuals at increased risk of adverse drug reactions (even when SCr concentration is in the normal range). For most drugs prescribed in primary care and for most patients of average age and body size, drug dosage adjustments based on eGFR should be similar to those based on Cockcroft–Gault. eGFR should not replace Cockcroft–Gault for determining dosage adjustments for critical-dose drugs that have a narrow therapeutic index. eGFR has resulted in important spin-off benefits, such as standardisation of laboratory creatinine assays and enhanced public and clinician awareness of CKD. Clinicians should be aware of the strengths, weaknesses and appropriate use of eGFR. Considerable research effort is being directed towards further refinement of eGFR.

David W Johnson MB BS(Hons), FRACP, PhD · Graham R D Jones MB BS, DPhil, FRCPA · Gavin J Becker MB BS, MD, FRACP · Timothy H Mathew MB BS, MRACP, FRACP

To the Editor: Gilbert and colleagues1 report thyroid function test results in a large number of pregnant women in Western Australia during the first trimester. While assessment of thyroid status is increasingly important in pregnancy, they do not present a strong enough argument for their reference ranges to be adopted. Their controls consisted of only 100 blood donors, and it is not clear whether these were age-matched with patients. Differences between pregnant and non-pregnant thyroid hormone ranges were too small to justify use of separate ranges. We assume from the article that the controls were not screened for thyroid antibodies. Prevalence of thyroid autoimmunity is high in women of reproductive age, whether or not they are pregnant.2 Serum thyrotropin (TSH) concentration is reduced in up to 20% of women during their first trimester, often with modestly increased thyroid hormones. The thyroid-stimulatory effect of human chorionic gonadotropin may help ensure adequate thyroxine delivery to the fetus. It is surely more important for clinicians to understand this than to have reference ranges that conceal normal physiological changes. Gilbert et al do not state whether patients with multiple or assisted-conception pregnancies were included — both are more likely to have abnormal thyroid test results.2 Their detection limit for TSH and the lower limit of normal differed by only 0.01 mU/L — they could therefore not reliably distinguish low TSH from suppressed TSH. They screened only 61% of pregnant women in WA. It is inconceivable that there was not a selection bias, as current guidelines3 advocate only screening high-risk groups such as those with a history of thyroid disease or previous poor obstetric outcome. Ethnic differences in TSH levels have been reported. However, data from the United States National Health and Nutrition Examination Survey (NHANES) suggest that TSH levels in Hispanics are no different to those of white people,4 contrary to what is suggested by Gilbert et al.1 Increased miscarriage risk may relate to autoimmunity itself, rather than altered thyroid function. The study by Negro et al5 is, to date, the only one showing a decrease in miscarriages when thyroxine is given to thyroid antibody-positive women. However, the TSH level before thyroxine was given was comfortably within the normal range reported by Gilbert et al. Publications in this complex area are only informative if they tell us something about thyroid physiology or about diagnosis and management of thyroid disorders. While laboratories must validate their reference ranges, it is unlikely that those reported by Gilbert et al could be generalised to the ethnically diverse and geographically dispersed Australian population. Also, as described,1 patients would have to be screened routinely for thyroid antibodies to ensure that the quoted ranges were applicable.

Richard L Kennedy · Usman H Malabu · David Porter

Objective: To determine the prevalence of elevated troponin levels after a marathon, and test for an association with reduced renal clearance.Design, setting and participants: Prospective observational study of entrants running the full (42 km) 2007 Perth Marathon, Western Australia.Main outcome measures: Elevated troponin levels (≥ 0.1 μg/L) after the race; pre- and post-race survey data, and biochemical parameters.Results: 27% of runners (92/346) enrolled in the study, of whom 88 (96%) completed it. Most were men (71%; 65/92); mean age was 43.1 years (SD, 9.8 years; range, 25–64 years) and mean body mass index (BMI) was 24.1 kg/m2. Raised troponin levels were seen in 32% of participants (28/88), the highest being 1.4 μg/L. The strongest predictor for developing elevated troponin levels was a decrease in weight (odds ratio [OR], 2.15; 95% CI, 1.27–3.65). Creatinine increase was also associated with elevated troponin levels (OR, 1.03; 95% CI, 1.01–1.06), but pre-race estimated glomerular filtration rate, age, sex, BMI, training factors, marathon experience and race time were not. Most runners (99%; 87/88) had elevated levels of ischaemia-modified albumin after the race.Conclusions: Troponin level increases were common among marathon finishers. The strongest predictors were weight loss and an increase in creatinine levels, suggesting that reduced renal clearance is an associated factor. Further study is needed to determine the clinical significance of these findings, and to understand the mechanism.

Kelley M Hubble MB BS · Daniel M Fatovich MB BS, FACEM · Jonathon M Grasko MB BCh · Samuel D Vasikaran MD, FRCPA

A 66-year-old, previously well man presented with colicky abdominal pain and vomiting. He was a cigarette smoker and consumed homemade spirits daily. On physical examination, the patient had poor dentition, a bluish pigment along the gingival line (Figure, arrow), and generalised abdominal tenderness with no peritonism; he was afebrile with a heart rate of 68 beats/min, blood pressure of 190/90 mmHg with no postural drop, and oxygen saturation of 99% in room air; and all other results were normal. Full blood examination revealed normocytic anaemia (haemoglobin, 90 g/L; reference range, 130–180 g/L) and basophilic stippling. The patient’s blood lead level was elevated at 7.10 μmol/L (reference range, < 0.48 μmol/L), but fell to 2.28 μmol/L after 3 weeks of treatment with the chelating agent 2,3-dimercaptosuccinic acid (DMSA). Burton’s lead line indicates lead poisoning and occurs due to deposition of lead sulfide, the result of a reaction between sulfur produced by oral flora and lead.1,2 The source of this patient’s lead exposure is unknown. Distilling equipment, especially for spirits, can be a source of lead exposure,3 but testing of this patient’s equipment ruled it out as a source.

Jayne E Camuglia · George Grigoriadis · Christopher P Gilfillan

To the Editor: We report the case of a 71-year-old woman who presented with a 3-week history of lethargy, subacute confusion and drowsiness. She was known to have a seizure disorder for which she had been taking lamotrigine 100 mg and sodium valproate 500 mg twice a day for 2 years. On examination, the woman was disoriented with regard to person and time, and had constructional apraxia and asterixis. The rest of the physical examination was unremarkable. A full blood count, electrolyte levels, coagulation parameters, arterial blood gas measurements and hepatitis serology were normal. Tests for immunological markers of autoimmune liver disease were negative. Liver function tests showed longstanding raised levels of alkaline phosphatase (158 U/L [reference range (RR), 30–110 U/L]) and γ-glutamyl transferase (434 U/L [RR, < 40 U/L]). Serum drug levels were sodium valproate 51.0 mg/L (therapeutic range, 50–100 mg/L) and lamotrigine 9.5 mg/L (therapeutic range, 3–14 mg/L). The venous blood ammonia level was 109 μmol/L (RR, < 50 μmol/L). A liver ultrasound scan was normal. Computed tomography of the brain showed microvascular changes and an old cortical infarct. An electroencephalogram (EEG) showed diffuse slowing, with a predominance of rhythmical theta activity and some delta activity, suggestive of encephalopathy. As hyperammonaemic encephalopathy secondary to sodium valproate therapy (VHE) was considered a possible diagnosis, sodium valproate treatment was discontinued. The patient’s confusion resolved completely and the asterixis disappeared within a week. At the same time, her blood ammonia level fell to 19 μmol/L and her EEG normalised. Eight months after discontinuing sodium valproate treatment, the woman was still asymptomatic. A subsequent percutaneous liver biopsy, to investigate her persistently abnormal liver function, showed features consistent with primary biliary cirrhosis. Sodium valproate is used not only for management of epileptic disorders but also for migraine prophylaxis and treatment of several psychiatric conditions. Although a generally well tolerated drug, it has a few well known side effects, including hyperammonaemia and, rarely, VHE.1-3 The possible pathophysiology of VHE has been described elsewhere.2 Gerstner et al reported on a series of 19 patients with VHE between 1994 and 2003.4 Review of the literature suggests that VHE is under-recognised, leading to considerable delay in the diagnosis of this potentially reversible condition.3,5 In our patient, it is reasonable to presume that sodium valproate precipitated the encephalopathy on a background of evolving unrecognised liver disease. The marked improvement in her clinical manifestations after discontinuation of valproate further supports this presumption. We have drawn attention to this case to highlight that VHE should be considered in patients presenting with confusion. Prompt measurement of the ammonia level and cessation of valproate treatment should be considered if clinically appropriate. Patients with previously unrecognised liver disease may be at particular risk. Acknowledgement: We thank Professor Peter Roberts-Thomson, Director of the Department of Immunology at Flinders Medical Centre, for his expert opinion and advice.

H S Subhash · Robert J Heddle · David W Schultz · John Ring · Campbell H Thompson

Objective: To determine the incidence of lactic acidosis in community-based patients with type 2 diabetes, with special reference to metformin therapy.Design: Substudy within a longitudinal observational study, the Fremantle Diabetes Study (FDS).Participants and setting: 1279 patients from a postcode-defined population of 120 097 people in Western Australia.Main outcome measures: Confirmed hospitalisation with lactic acidosis identified through the WA Data Linkage System during two periods: (1) from study entry, between 1993 and 1996, and study close in November 2001; and (2) from study entry to 30 June 2006.Results: At entry, 33.3% of patients were metformin-treated, and 23.1% of these had one or more contraindications to metformin (55.1% and 38.0%, respectively, after 5 years’ follow-up). Five confirmed cases of lactic acidosis were identified during 12 466 patient-years of observation; all had at least one other potential cause, such as cardiogenic shock or renal failure. From study entry to close, the incidence was 0/100 000 patient-years in both metformin-treated and non-metformin-treated patients. Between study entry and 30 June 2006, incidence was 57/100 000 patient-years (95% CI, 12–168) in metformin-treated patients and 28/100 000 patient-years (95% CI, 3–100) in the non-metformin-treated group, an incidence rate difference of – 30 (– 105 to 46) (P = 0.4).Conclusion: The incidence of lactic acidosis in patients with type 2 diabetes is low but increases with age and duration of diabetes, as cardiovascular and renal causes become more prevalent. Metformin does not increase the risk of lactic acidosis, even when other recognised precipitants are present.

Niklaus Kamber MD · Wendy A Davis MPH, PhD · David G Bruce MD, FRACP · Timothy M E Davis MRCP, DPhil, FRACP

A 44-year-old man with a history of childhood brain injury presented with dysarthria, confusion, reduced oral intake and reduced mobility after a week of heatwave conditions. He had severe hypernatraemia and raised serum creatine kinase levels, consistent with rhabdomyolysis. In most previous case reports linking hypernatraemia and rhabdomyolysis, other factors have potentially contributed. From the available evidence, severe hypernatraemia alone appears sufficient to induce muscle injury. Clinical recordA 44-year-old man presented to a rural hospital with a 48-hour history of reduced mobility, dysarthria, confusion and reduced oral intake. He had sustained a traumatic brain injury at the age of 6 years and had intellectual impairment, mild right hemiplegia and post-traumatic epilepsy, but had not experienced a seizure for many years. Ambient temperatures were anecdotally reported to be up to 48°C during the week before presentation. The patient was cared for by his brother, who confirmed there had been no recent seizures, exertion, significant falls or prolonged recumbency. His only regular medication was rabeprazole. At presentation, he was dehydrated, febrile (temperature, 38°C), anuric and hypotensive, with a blood pressure of 90/50 mmHg. Initial blood biochemical tests showed the following levels: serum sodium, > 180 mmol/L (reference range [RR], 135–145 mmol/L); serum potassium, 4.3 mmol/L (RR, 3.2–4.5 mmol/L); bicarbonate, 13 mmol/L (RR, 22–33 mmol/L); haemoglobin, 204 g/L (RR, 135–180 g/L); and serum creatinine, 455 μmol/L (RR, 70–120 μmol/L). Creatine kinase (CK) concentration was 13 000 U/L (RR, < 200 U/L), while troponin I was minimally elevated, with a peak value of 0.8 μg/L (RR, < 0.2 μg/L), consistent with rhabdomyolysis. Laboratory technical difficulties precluded a urinary myoglobin assay. A snake venom assay was negative, and the patient’s coagulation profile was normal. On clinical examination, there was no evidence of trauma or compartment syndrome. Initial treatment comprised fluid resuscitation (with a total of 5 L intravenous fluid) and empirical intravenous antibiotics. The patient was transferred to a tertiary hospital intensive care unit, where he received further fluid replacement, electrolyte correction and renal replacement therapy. A single brief generalised tonic–clonic seizure several hours after his arrival was treated with phenytoin. The CK concentration peaked at 31 200 U/L. Renal function recovered to baseline over 6 weeks, and the man was ultimately discharged home from the hospital’s rehabilitation unit, having returned to his premorbid functional state. DiscussionThe patient developed severe dehydration and hypernatraemia as a result of increased insensible losses and inadequate fluid intake during a week of extreme weather conditions, despite having unrestricted access to water. Whether he had a degree of hypothalamic hypodipsia as a result of acquired brain injury is uncertain. A careful history and physical examination did not suggest a single obvious cause for his rhabdomyolysis. Core temperature was not sufficiently elevated to favour heat stroke as a diagnosis. The CK concentration was already raised before the seizure, which was not prolonged. A review of the literature identified hypernatraemia as a potential contributor. Rhabdomyolysis is a clinical and laboratory syndrome characterised by muscle necrosis and release of intracellular muscle constituents into the circulation. It ranges in severity from asymptomatic elevation of CK concentration to severe life-threatening cases associated with extreme rise in CK concentration, myoglobinuria and acute renal failure. The most common causes include muscle compression or trauma, hyperexertional states (such as prolonged seizure or extreme exercise), metabolic and inflammatory myopathies, heat stroke, and drug- or toxin-related muscle injury.1 Severe electrolyte derangements, including hyponatraemia, hypokalaemia and hypophosphataemia, are also described, with the proposed mechanism being cell membrane disruption as a result of deranged sodium–potassium–ATPase pump function.2 Multiple case reports and series have linked hypernatraemia and rhabdomyolysis.3-5 Most cases have been in the setting of hyperosmolar states, such as those associated with diabetes mellitus. In many cases, other factors have potentially contributed to the development of rhabdomyolysis, including recumbency resulting from altered levels of consciousness or seizures. Evidence for a direct causal link between hypernatraemia and rhabdomyolysis is provided by three reported cases of central diabetes insipidus resulting in severe hypernatraemia and rhabdomyolysis in the absence of other potential causes.6-8 In all cases, the serum sodium concentration was greater than 180 mmol/L. In 1992, Abramovici and colleagues, reporting a case series of 18 patients with hypernatraemia, showed a significant linear correlation between serum sodium concentration and serum CK level. They were then able to induce rhabdomyolysis in laboratory rats by rendering them severely hypernatraemic after fasting and intraperitoneal injection of hypertonic saline. Pre- and post-injection biochemical analyses confirmed that only serum sodium concentration and CK concentration were altered significantly.9 In summary, rhabdomyolysis can be induced by a range of insults, and is often multifactorial. From the available evidence, severe hypernatraemia alone appears sufficient to induce muscle injury, and should be considered as a potential cause.

Jason P Denman BAppSc, MB BS(Hons)

Since publication of the Australasian Creatinine Consensus Working Group’s position statement in 2005, most Australasian laboratories now automatically report an estimated glomerular filtration rate (eGFR) (based on the Modification of Diet in Renal Disease [MDRD] formula) with results of serum creatinine tests in adults. Anecdotal evidence suggests that automatic reporting of eGFR helps to identify asymptomatic kidney dysfunction at an earlier stage and to develop rational and appropriate management plans. Changes to the measurement and calibration of serum creatinine assays and issues regarding implementation of eGFR in clinical practice led the Australasian Creatinine Consensus Working Group to reconvene in 2007. The recommendations contained here build on the original 2005 position statement and consolidate the role of eGFR in clinical practice. The Working Group recommends that the eGFR upper reporting limit be extended to 90 mL/min/1.73 m2, with eGFR values above this amount being reported as “> 90 mL/min/1.73 m2”, rather than as a precise figure. The Working Group has concluded that it is currently premature to recommend age-related decision points for eGFR. However, it is appropriate to advise medical practitioners that, in people aged ≥ 70 years, an eGFR in the range 45–59 mL/min/1.73 m2, if stable over time and unaccompanied by other evidence of kidney damage, may be interpreted as consistent with a typical eGFR for this age group and is unlikely to be associated with chronic kidney disease-related complications. Pending publication of validation studies, the Working Group recommends that Australasian laboratories continue to automatically report eGFR in Aboriginal and Torres Strait Islander peoples and other ethnic groups. The Working Group supports the use of eGFR to assist drug dosing decision making in general practice.

on behalf of the Australasian Creatinine Consensus Working Group

Victor Wynn, a physician, scholar and philanthropist who was one of the pioneers of the study of metabolism, died in London on 6 October 2006 of heart failure. Born in Melbourne on 12 October 1920, Victor attended Wesley College and the University of Melbourne. After graduating in medicine in 1943, he spent 4 years as a Medical Officer in the Australian Army. He was appointed as a Research Fellow at the Department of Physiology, University of Melbourne, in 1948. In 1950, Victor was awarded a Nuffield Fellowship to conduct research at St Mary’s Hospital, London. He was appointed to the staff of St Mary’s Hospital Medical School in 1953, then became Reader in Human Metabolism in 1960, Director of the Alexander Simpson Laboratory for Medical Research in 1965, and Professor of Human Metabolism in 1969. During this time, he led the establishment of quantitative clinical biochemistry on a large scale and integrated this with clinical research and patient care on an equally large scale. Victor’s interest in the management of surgical patients led to research into the new anabolic steroids. He demonstrated their potent and undesirable effects in relation to sugar and fat metabolism and was among the first to caution against their widespread use. His research also suggested major adverse effects of taking the contraceptive pill. He undertook large, detailed studies of the association between the pill and the risk of heart disease. International prominence followed, with several appearances on the BBC’s David Frost program. The resulting public scare led the Health Secretary to accuse Victor of making “10 000 women pregnant in a single night”. He was also prescient in other areas. In the early 1970s, he was urging cardiologists to pay more attention to blood cholesterol levels; 25 years later, measuring blood lipids would become as critical in evaluating patients with heart disease as measuring electrolytes had been in monitoring surgical patients. Throughout the 1970s and 1980s, Victor increasingly devoted his energies to fundraising, setting up environments in which partnerships between clinical care and high quality laboratory measurement could be pursued more effectively. His department at St Mary’s was the model, combining ward investigation, laboratory facilities, and data acquisition and computing facilities that were, at the time, on an unprecedented scale for medical school research. This concept was extended and enhanced on his retirement, in 1986, with the establishment of the Cavendish Clinic. The Clinic was affiliated with the UK National Heart and Lung Institute, renamed the Wynn Institute and subsequently incorporated into the Faculty of Medicine of Imperial College, London. Victor established two charities, the Heart Disease and Diabetes Research Trust and the Atherosclerosis Research Trust, which contributed over £15 million to research. They provided continuing support to Imperial College, London, and, in 2001, the financial base for a new centre, the Wynn Department of Metabolic Cardiology at the Baker Heart Research Institute, Melbourne. In May 2006, he was made a Fellow of Imperial College, London — the highest honour the College can bestow. Victor had a driving, single-minded personality that was not thwarted by three decades of his own experience of heart disease, from which he began to suffer at the age of 55. He is survived by his wife Marianne, Emeritus Professor of German at the University of London, and daughter Nicola.

John R Rigg

Nanomaterials — a wide variety of materials with a diameter of less than 100 nm — have unique properties. Nanotechnology is being promoted as the technology that will drive the next industrial revolution. Nanomaterials may have unique biological activities, but little research has been undertaken to investigate their potential effects on human health and the environment. Many seminal reports have identified gaps in our knowledge, and a large multidisciplinary effort will be required to undertake the necessary research to assist the framing of regulatory models to deal with any novel risks.

Brian G Priestly MPharm, PhD · Andrew J Harford BAppSc, PhD · Malcolm R Sim PhD, FFOM

A 50-year-old man was transferred to the intensive care unit with high anion gap metabolic acidosis. Investigations suggested a diagnosis of pyroglutamic acidaemia. Factors contributing to the acidosis were medications (paracetamol and flucloxacillin), sepsis and renal failure. The acidosis resolved with supportive therapy and withdrawal of the drugs. It is important to recognise this treatable aetiology of metabolic acidosis. Clinical recordA 50-year-old man with cerebral palsy, intellectual impairment and epilepsy was referred to hospital with a 1-week history of fever, chills, rigors, haematuria and loin pain. His usual medications included phenytoin 300 mg/day, phenobarbitone 30 mg/day and carbamazepine 1200 mg/day. There was no history of prior renal disease. At hospital admission (Day 1), he was conscious, in no obvious distress, and afebrile. He was dehydrated and tachypnoeic (respiratory rate, 22 breaths/minute), but haemodynamically stable. There was no pallor, jaundice or cyanosis. Cardiorespiratory examination was unremarkable. Abdominal examination revealed tenderness in the left renal angle, left loin and right upper quadrant with no features of peritonism. Key initial (and subsequent) screening investigations are summarised in Box 1. Of note was neutrophilia and significant renal impairment (glomerular filtration rate, 28 mL/min by MDRD 4-variable equation). Urinalysis showed sterile pyuria, haematuria (dysmorphic red blood cells on microscopy) and proteinuria (3.46 g following 24-hour collection). A chest x-ray (CXR) showed mild generalised bronchial wall thickening, with no focal parenchymal opacity. Treatment with empirical broad-spectrum intravenous antibiotics (ceftriaxone and gentamicin) was initiated for suspected urinary tract infection following blood and urine cultures. A computed tomography (CT) scan on Day 1 revealed a 2.3 cm simple cyst in the upper pole of the right kidney, multiple nodules in the lung bases and a small left pleural effusion. A vasculitic work-up, including assessment of antinuclear antibody, extractable nuclear antigen, antibodies to double-stranded DNA, antineutrophil cytoplasmic antibodies and complement levels, did not assist in diagnosis. Urine culture was negative, so a renal biopsy was performed to establish the aetiology of the acute nephritic syndrome, consistent with IgA nephropathy with mild activity (segmental crescents/necrotising lesions in two of 14 glomeruli), but without scarring. No treatment was indicated. In view of the persistent fever on Day 3, a repeat CXR was performed. A small left-sided effusion was noted and pleural fluid aspirate was consistent with an exudate (pleural fluid white cell count [WCC], 16.6 × 109/L; 85% neutrophils; total protein, 37 g/L; lactate dehydrogenase [LDH], 420 U/L), which was presumed secondary to an underlying pneumonic process. Intravenous flucloxacillin was commenced at 2 g/day to broaden the gram-positive antibiotic cover and continued for 11 days. Blood, urine and pleural fluid cultures were negative. Despite initial clinical and laboratory improvement, the fever recurred on Day 7 with a radiographically visible increase in the pleural effusion size. Repeat pleural aspirate confirmed an empyema (pleural fluid pH 6.4; LDH, 833 U/L; glucose, 0.2 mmol/L) requiring intercostal catheter insertion. However, there was minimal further drainage, despite intrapleural streptokinase administration. On Day 14, ceftriaxone and gentamicin were changed to empirical timentin and ciprofloxacin because of persistent fever and rising WCC. Flucloxacillin was increased to 4 g/day. Oral paracetamol (1 g every 6 hours as required) and subcutaneous fentanyl were administered for pain relief. On Day 18, deteriorating renal function and conscious state necessitated transfer to the intensive care unit (ICU). Investigations at ICU admission (Box 1) revealed a severe high anion gap (42 mmol/L) metabolic acidosis. Arterial blood gas analysis (on 100% inspired oxygen) showed a pH of 7.31, PaO2 242 mmHg, PaCO2 12 mmHg, and HCO3 5.6 mmol/L. Flucloxacillin and paracetamol were ceased, and intravenous vancomycin was commenced. Intravenous bicarbonate infusion (25 mL/hour), commenced in the ward for the acidosis, was continued. With supportive therapy (fluids, oxygen, antibiotics), the patient improved over the next 36 hours and the metabolic acidosis resolved. Following stabilisation, the patient underwent decortication of the left pleura. Histopathology was consistent with an organising fibrinous pleuritis. No bacteria were seen. Decortication was complicated by significant bleeding, requiring massive transfusion. After surgery, the patient’s renal function, respiratory function and conscious state steadily improved; he was extubated 5 days after decortication. Recovery was complicated by protracted vomiting. Endoscopy confirmed a Barrett’s oesophagus and small hiatus hernia; he improved with a proton-pump inhibitor. In the absence of further respiratory compromise, he was discharged home. DiagnosisThe cause of the high anion gap metabolic acidosis at ICU admission was not immediately apparent. Serial evaluation of biochemical markers showed worsening renal function. However, even with a creatinine level of 0.541 mmol/L, the expected level of unmeasured anions was only 10–19 mmol/L and was insufficient to explain an anion gap of 42 mmol/L and the severity of the metabolic acidosis. Lactate (0.7 mmol/L) and blood glucose levels (6.1 mmol/L) were not elevated, and urinalysis was negative for ketones, suggesting that lactic or keto-acidosis were unlikely causes (blood ketones were not measured). There was no history of salicylate administration or ethylene glycol, ethanol or methyl alcohol consumption. Case-note review indicated that the patient had received a total of 8 g of paracetamol and 16 g of flucloxacillin in the 4 days before ICU admission. Ongoing sepsis and worsening renal failure, in combination with these drugs, suggested a possible diagnosis of pyroglutamic acidaemia (PGA). Urine pyroglutamic acid levels, highly elevated 36 hours after ICU admission (Box 1) remained elevated 10 days later, although the values had decreased significantly. Plasma pyroglutamic acid levels were also markedly elevated 36 hours after ICU admission (Box 1). The very high urine and plasma pyroglutamic acid levels supported our diagnosis of PGA. Red cell glutathione synthetase activity was normal (5.6 μmol/g haemoglobin; reference range, 4.2–9.8 μmol/g haemoglobin), suggesting that it was unlikely that this patient had a hereditary disorder of the γ-glutamyl cycle. DiscussionHigh anion gap metabolic acidosis is frequently encountered in critical care practice. Recently, there have been several reports of high anion gap acidosis resulting from excess production of 5-oxoproline, and termed “pyroglutamic acidaemia”.1-5 This acidaemia is most frequently reported with paracetamol therapy,1 but has also been associated with flucloxacillin2 and vigabatrin,3 particularly in the setting of severe sepsis, renal or hepatic dysfunction.4 The reported inciting dose of paracetamol has been variable: 8 g of paracetamol daily for 3 weeks in one study,6 and a cumulative dose of 20.8 g of paracetamol over 2 weeks in another.7 In a series of 11 patients with transient oxoprolinuria, all patients were taking paracetamol, with most receiving therapeutic dosages.8 A serum paracetamol level of > 200 μmol/L was seen in only one of the eight patients in whom paracetamol levels were checked. Our patient received a cumulative dose of 8 g of paracetamol over 4 days, and it is likely that PGA was precipitated by a combination of factors, including sepsis, renal dysfunction, and co-administration of flucloxacillin. PGA also occurs with genetic deficiency of either glutathione synthetase or 5-oxoprolinase.5 However, not all causes of 5-oxoprolinuria are necessarily associated with acidaemia. The mechanism of non-hereditary PGA is probably multifactorial. Suppression of glutathione levels because of sepsis, as seen in animal models of polymicrobial sepsis,9 may have contributed to the development of PGA in our patient. Flucloxacillin could have further compounded this acidosis by inhibiting the breakdown of pyroglutamic acid by 5-oxoprolinase.2 The role of paracetamol in PGA is more complex. The metabolite of paracetamol, N-acetyl benzoquinoneimine, reacts irreversibly with glutathione. Under normal circumstances, glutathione depletion leads to increased γ-glutamyl cysteine synthetase activity and excessive production of γ-glutamyl cysteine (Box 2). However, under altered conditions, glutathione synthetase activity becomes rate-limiting, leading to the conversion of γ-glutamyl cysteine to 5-oxoproline by γ-glutamyl cyclotransferase.5 Our patient’s antiepileptic medications, which are known hepatic enzyme inducers and metabolised via CYP2E1, may have further compromised glutathione availability by decreasing glutathione stores and competing with paracetamol for metabolism. Renal impairment may also be important. Renal tubular epithelial dysfunction may impair intracellular glutathione re-formation (a high ATP-requiring state), leading to accumulation of 5-oxoproline and prompt excretion (because of its small molecular size) into the urine, peritubular capillaries and systemic circulation. The use of N-acetyl cysteine to treat PGA has been advocated to replenish glutathione stores by supplying cysteine for glutathione synthesis. Another theoretical treatment option is the use of cysteamine, which increases cytosolic cysteine and restores substrate availability for the glutamate pathway, normalising pyroglutamic acid levels. As PGA can be easily missed in a critically ill patient, where several factors may contribute to a metabolic acidosis, a high index of suspicion is required to diagnose this condition. PGA should be considered in the differential diagnosis of high anion gap acidosis, especially when the levels of organic acids do not sufficiently account for the degree of anion gap and when there is co-administration of drugs such as paracetamol and flucloxacillin. Where PGA is suspected, the offending drugs should be withdrawn and treatment with N-acetyl cysteine considered. 1 Investigations* Day 1 Hospital admission Day 18 ICU admission Day 63 On recovery Reference range Haematology Haemoglobin (g/L) 125 115 120 135–175 White cell count (× 109/L) 13.6 24.7 7.82 4–11 Neutrophil count (× 109/L) 11.1 22.75 6.09 1.8–7.5 International normalised ratio 1.2 7.6 1.0 0.8–1.2 APTT (s) 27 65 26 24–37 Fibrinogen level — 5.7 — 1.5–4.0 D-dimer FDP — 2.15 — < 2.0 Biochemistry Sodium (mmol/L) 134 138 137 137–145 Potassium (mmol/L) 3.9 2.8 4.1 3.5–4.9 Chloride (mmol/L) 97 93 99 100–109 Bicarbonate (mmol/L) 23 6 29 22–32 Urea (mmol/L) 9.1 18.6 2.7 2.7–8.0 Creatinine (mmol/L) 0.210 0.541 0.100 0.05–0.12 Gamma GT (U/L) 152 92 116 0–60 Albumin (g/L) 25 17 23 34–48 Lactate dehydrogenase (U/L) 252 293 210 110–230 Serum amylase (U/L) — 119 — 20–100 C-reactive protein (mg/L) 290 160 47 < 10 Anion gap (mmol/L) 18 42 13 7–17 Lactate level (mmol/L) — 0.7 — 0.2–2.0 Serum pyroglutamic acid level† (μmol/L) — 11 010 — 15–215 Urine pyroglutamic acid level† (μmol/mmol creatinine) — 20 495 13 103 < 100 * Platelet count, bilirubin, alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase and creatinine kinase were normal when measured. † Initial serum and urine pyroglutamic acid levels were measured 36 hours after admission to the intensive care unit, and repeat urine test was performed on Day 10. Serum and urine pyroglutamic acid levels not measured at discharge. — = Not measured. Bold indicates highly abnormal results. APTT = activated partial thromboplastin time. FDP = fibrinogen degradation products. GT = glutamyl transpeptidase. ICU = intensive care unit. 2 The γ-glutamyl cycle: mechanism of oxoprolinuria Sepsis and paracetamol reduce glutathione levels, lifting feedback inhibition of γ-glutamyl cysteine synthetase. Excess γ-glutamyl cysteine is converted by γ-glutamyl cyclotransferase to 5-oxoproline, the build-up of which leads to acidaemia and oxoprolinuria. Flucloxacillin may inhibit further the rate-limiting enzyme 5-oxoprolinase.

John V Peter MD, DNB, FRACP · Natasha Rogers MB BS · Shailesh Murty MB BS, MD · Rosemarie Gerace BSc · Richard Mackay FRACP · Sandra L Peake BM BS, FJFICM, PhD

To the Editor: I agree with Jones1 that the body surface area (BSA) formula printed in the position statement on reporting of estimated glomerular filtration rate (eGFR)2 is wrong, even though the authors say that he is mistaken.3 As stated by Jones, the correct formula4 for BSA in m2, for a body weight W kg and height H cm is: (i) BSA = W0.425 × H0.725 × 0.007184. However, the position statement2 gave the following formulas: (ii) BSA = W0.425 × H0.725 × 0.007184/1.73; and (iii) Uncorrected eGFR = GFR estimate (mL/min/1.73m2) × BSA. It appears that the denominator “1.73” has migrated from formula (iii) to formula (ii), so in fact both of these formulas are incorrect. This is potentially misleading for doctors and others who may want to calculate the eGFR for someone who is unusually big or small. Formula (iii) should in fact be: (iii) Uncorrected eGFR = GFR estimate (mL/min/1.73m2) × BSA/1.73. It is interesting that the same two errors in BSA calculations are present on the US National Kidney Disease Education Program website,5 which was presumably the source of the formulas used by the Australian Creatinine Consensus Working Group.

Alan McNeil PhD, FRACP, FRCPA

In reply: McNeil draws attention to the detail in the correction factor we published in an attempt to assist users to “uncorrect” the eGFR derived from the MDRD (Modification of Diet in Renal Disease) equation used in calculating GFR from a serum creatinine concentration. Recalculating the eGFR to remove the adjustment for body surface area (BSA) in an individual is unnecessary except at extremes of body size.1 Readers can be reassured that the formulas published in the position statement,2 if used as directed, will not lead to any error. However, it would have been clearer if we had labelled the “BSA” equation as “correction factor” instead of “BSA”. In the position statement2 it can be misinterpreted that the BSA formula has a denominator, whereas, when used primarily to calculate BSA, it of course does not. Both versions of the formulas (ours in the position statement and McNeil’s) therefore lead to identical answers. The reader can choose which one to use.

Timothy H Mathew MB BS, MRACP, FRACP · Graham Jones MB BS, DPhil, FRCPA · David Johnson MB BS, FRACP, PhD

Huy A Tran Director, Hunter Area Pathology Service; and Associate Professor, Department of Clinical Chemistry, University of Newcastle, John Hunter Hospital, Locked Bag 1, Hunter Region Mail Centre, NSW 2310. huy.tranAThnehealth.nsw.gov.au To the Editor: The recent article by Roberts et al1 requires further comment. In anorexia nervosa, hypercalcaemia is extremely unusual because patients are likely to be under- or malnourished, with consequent hypocalcaemia and hypovitaminosis D, rather than the opposite, as implied by the authors. In one of their references,2 hypercalcaemia is only briefly included, and the mechanism is not discussed or substantiated. Another of their references3 does not include hypercalcaemia at all as a metabolic disturbance. In addition, hypercalcaemia in itself is not a diagnosis, and indicates a significant underlying pathophysiological disturbance whose differential diagnoses need to be carefully dissected. Where there are problems with the interpretation of calcium homoeostasis, such as renal impairment and hypoalbuminaemia, ionised calcium should be measured because it is the physiologically active agent. In the first patient described by Roberts et al, although the investigations are incomplete, primary hyperparathyroidism (PHPT) needs to be carefully considered, as the parathyroid hormone (PTH) level is not normal in the setting of hypercalcaemia. The normal physiological response would dictate that the PTH level should be low to suppressed. Nephrocalcinosis and renal impairment then fit snugly into the diagnosis of PHPT.4 Phosphate level, expected to be low in this condition, might have been masked by exogenous phosphate supplement. For Patient 2, stool electrolyte analysis could further support the presence of laxative misuse and aid in the interpretation of urinary results. Faecal fluid in this situation should be high in sodium, potassium and calcium concentrations. The low urinary sodium and calcium levels are therefore appropriate, and indicate relatively intact tubular function. The diagnosis of hypercalcaemia is thus difficult without a PTH measurement and in the presence of gastrointestinal confounders, even if all investigations were available. Nevertheless, familial benign hypocalciuric hypercalcaemia (FBHH) is a strong probability given the low urinary calcium excretion, especially before iatrogenic manipulation of calcium and phosphate homoeostasis. Nephrocalcinosis can theoretically occur in FBHH.5 It is important that the diagnosis is made in both cases, so that a familial study can be carried out if indicated given the patients’ age. One may also wonder if the intermittent hypercalcaemia contributed to or aggravated the psychiatric disturbance in both patients.

Huy A Tran

Matthew A Roberts,* Campbell R Thorpe,† Duncan P MacGregor,‡ Nick Paoletti,§ Francesco L Ierino¶ * Nephrologist, ‡ Director of Anatomical Pathology, § Psychiatrist, ¶ Deputy Director of Nephrology, Austin Health, Studley Road, Heidelberg, VIC 3084; † Psychiatrist, Child and Adolescent Mental Health Service, The Alfred Hospital, Melbourne, VIC. frank.ierinoATaustin.org.au In reply: Disturbances of calcium metabolism in anorexia nervosa are complex, particularly with associated renal insufficiency. Although hypocalcaemia is observed in patients with anorexia nervosa, our article attempted to highlight nephrocalcinosis and hypercalcaemia. We agree that hypercalcaemia is not in itself a diagnosis, and identifying the underlying pathology is essential. Ingestion of vitamin D preparation remains a likely explanation for the hypercalcaemia observed in Patient 1; however, primary hyperparathyroidism was considered as a possible differential diagnosis. Patient 1 had two normal parathyroid hormone tests in the setting of hypercalcaemia and renal impairment. This is consistent with secondary hyperparathyroidism and vitamin D ingestion as documented. The coexistence of primary hyperparathyroidism cannot be excluded. Ionised calcium may be a useful measure if the patient had hypoalbuminaemia, and this would be our normal practice. Patient 2 had ionised calcium measured twice (one result high, one low), but these added little to the case description and message of the article. Faecal electrolytes were not measured in Patient 2. However, we acknowledge the potential utility of this investigation when interpreting electrolyte disorders. We also agree that familial or genetic conditions should be considered if clinically appropriate.

Matthew A Roberts · Campbell R Thorpe · Duncan P MacGregor · Nick Paoletti · Francesco L Ierino

This case describes refeeding syndrome associated with volitional oral nutrition in a patient with chronic alcoholic abuse admitted for detoxification. Refeeding syndrome is an under-recognised and undertreated condition1-5 of severe, acute electrolyte, fluid-balance and metabolic abnormalities in chronically malnourished patients undergoing renutrition. Refeeding syndrome was first described in Japanese prisoners during World War II.6 Since then, it has been described in patients being refed after hunger strikes, starvation after being lost, chronic alcoholism, anorexia nervosa, malignancy, kwashiorkor and marasmus and in obese patients who have had duodenal switch operations.4,5 Reports conflict over whether it is more common following parenteral7 or enteral tube4 nutrition, but descriptions following volitional oral refeeding are less frequent. In people in a chronically starved state, insulin secretion is reduced in parallel with low carbohydrate intake. Fat catabolism predominates, and free fatty acids and ketone bodies replace glucose as the major energy source. If starvation is severe, body stores of phosphate, potassium and magnesium may be depleted, although serum levels are often maintained.3-5 With refeeding, there is a shift back to carbohydrate metabolism and an increase in insulin levels. Insulin stimulates the movement of phosphate, potassium and magnesium into the cells, leading to a fall in their serum concentrations.2 In addition, tissue anabolism increases cellular demand for phosphate, glucose, potassium and water.1 Hyperphosphaturia may occur with alcoholism,7,8 and thiamine, required for the intracellular transport of glucose, may be depleted.9 The principal biochemical hallmark of refeeding syndrome, as seen in this case, is severe, acute hypophosphataemia that usually occurs within 3–4 days of refeeding.2,3,10 This is often associated with hypokalaemia, hypomagnesaemia, sodium and fluid retention, thiamine deficiency and hyperglycaemia. Phosphate is the body’s major intracellular anion.4 Daily oral phosphate intake is about 1000–1400 mg, the major sources being meat, poultry, eggs, cereals and dairy products.4 Wine contains little phosphate.11 Phosphate is found in phospholipids, nucleic acids, adenosine triphosphate and 2,3-diphosphoglycerate in red blood cells. It is important for intracellular buffering, enzymatic phosphorylation, glucose metabolism, nervous system conduction and leucocyte function. Hypophosphataemia-induced depletion of 2,3-diphosphoglycerate in erythrocytes results in a left shift of the haemoglobin/oxygen dissociation curve, increasing haemoglobin affinity for oxygen and predisposing to local tissue hypoxia.1,2,4 However, the clinical manifestations of refeeding syndrome are varied and non-specific (Box 3). Potentially life-threatening sequelae include acute cardiac failure, respiratory failure, Wernicke’s encephalopathy, sepsis and acute renal failure. Sudden cardiac death has been reported in two chronically malnourished patients experiencing acute hypophosphataemia after initiation of total parenteral nutrition.12 Although non-specific, we believe the constellation of symptoms and signs observed in our patient is typical of refeeding syndrome. Most importantly, acute, severe hypophosphataemia not present on admission was noted 4 days after oral refeeding with a ward diet. The presence of a serum phosphate level of 0.15 mmol/L in our patient represents extreme hypophosphataemia. (The lowest published level we are aware of in a patient who survived is 0.07 mmol/L.11) Given the “low normal” value on admission and the patient’s risk factors for refeeding syndrome, the serum phosphate level should have been monitored more closely during the first few days of admission. We did consider several differential diagnoses. Although hypophosphataemia is commonly seen in sepsis,14 clinical and haematological evidence suggested that the patient’s respiratory infection had largely resolved by Day 4. Acute respiratory alkalosis may also cause hypophosphataemia,15 but was unlikely in this case, in view of the normal serum phosphate level on admission. Severe hypokalaemia was already being corrected by intravenous replacement from the day of admission. The development of paraesthesiae, myalgias, groin candidiasis, diarrhoea and sinus tachycardia (which may have indicated incipient cardiac failure4,9) was consistent with the diagnosis of refeeding syndrome.4 Unfortunately, the creatinine kinase level was not measured to exclude rhabdomyolysis. Cerebellar signs may have been secondary to alcoholic degeneration or mild Wernicke’s encephalopathy. Management of refeeding syndrome includes slowing of caloric intake, correcting electrolyte and metabolic abnormalities, monitoring fluid balance and treating complications. Thiamine and B-complex vitamins should be prescribed prophylactically before refeeding.4 Interestingly, the early administration of intramuscular thiamine for chronic alcoholism may have protected our patient against Wernicke’s encephalopathy secondary to refeeding syndrome. Ideally, patients at risk of developing refeeding syndrome should be identified and a prophylactic low-caloric low-carbohydrate dietary regimen implemented.3 Initially, 85 kJ per kilogram of body weight per day, with a generous protein allowance (1.2–1.5 g protein per kilogram of body weight per day), has been suggested.4,13 Caloric intake can then be gradually increased over the following 1–2 weeks, ensuring that clinical and biochemical parameters are closely monitored.4,12,13 It is important to note that most current recommendations are based on parenteral or enteral tube nutrition. Protocols are not well developed for volitional oral refeeding. However, “slow” refeeding in these patients could be achieved by providing a similar low daily caloric intake with reduced food portions. Ideally, an experienced dietitian should be consulted.4 In our case, a dietitian was not available on site, and, given the prompt correction of electrolyte abnormalities and absence of acute cardiac failure, no change to diet was made. Levels of serum electrolytes, urea and creatinine should be monitored at least daily in the acute phase. Prophylactic phosphate and potassium supplementation is often required at the time of refeeding in high-risk patients. Phosphate replacement is recommended if serum levels are below 0.3–0.5 mmol/L3,4,10 or if the patient is symptomatic. As oral replacement at these levels is often inadequate, intravenous replacement is advised.7,10 Complications of overzealous intravenous phosphate replacement may include hyperphosphataemia, hypocalcaemia, tetany, hypotension, hyperkalaemia, hypernatraemia, renal failure and metastatic calcification.2,10 Although successful intravenous regimens based on patient weight and serum phosphate levels in intensive care settings have been described,15 these are often complicated and impractical for ward patients. Terlevich et al10 described the use of 50 mmol intravenous phosphate over 24 hours in 30 ward patients with refeeding syndrome and normal renal function. Twenty-eight patients safely achieved a serum phosphate level above 0.5 mmol/L within 72 hours. We used 42 mmol intravenous phosphate over 36 hours to normalise serum levels in our patient. While less aggressive than the protocol described by Terlevich et al, it was deemed sufficient given that the patient was largely asymptomatic and that serum phosphate levels were improving. Intravenous phosphate was dispensed on site in 14 mmol aliquots, and prescribing this amount over 12 hours simplified the dosing regimen. Clinical diagnosis of refeeding syndrome requires a high index of suspicion.1 Its hallmark of acute, severe hypophosphataemia in chronically malnourished patients after refeeding may occur even in patients who are largely asymptomatic and orally fed. Prevention of morbidity and, in some cases, death requires careful management of diet, vitamin intake and electrolyte and fluid balance. Lessons from practice Refeeding syndrome is a potentially lethal condition in chronically malnourished patients undergoing renutrition. The syndrome is under-recognised and undertreated. Electrolyte levels should initially be monitored daily in at-risk patients, as acute, profound hypophosphataemia may develop even in asymptomatic patients. Regimens for volitional oral refeeding are not well developed, but a prophylactic low-caloric (85 kJ per kilogram of body weight per day), low-carbohydrate diet has been advised. Prophylactic thiamine, phosphate and potassium supplementation is often required for at-risk patients. Patients with serum phosphate levels below 0.3–0.5 mmol/L or symptoms of hypophosphataemia require intravenous phosphate replacement. 1 Serum electrolyte levels over the first 8 days after admission Day Electrolyte Reference range 1 4 8 Potassium (mmol/L) 3.6–5.1 2.4 3.5 3.9 Calcium (mmol/L) (corrected for serum albumin) 2.25–2.58 2.27 2.60 2.60 Magnesium (mmol/L) 0.74–1.03 0.71 0.69 0.70 Phosphate (mmol/L) 0.80–1.50 0.84 0.15 1.56 2 Serum phosphate levels over the first 8 days after admission* * Dotted line indicates the direction of change only (no data were available for Days 2 and 3). 3 Clinical features of refeeding syndrome4 Clinical feature Possible mechanisms Cardiovascular Acute cardiac failure Fluid retention (secondary to carbohydrate intake1,2,4 and hyperinsulinaemia9), arrhythmias, cardiomyopathy1,2,4 Arrhythmias, sudden cardiac death3,12 Electrolyte disturbance1,2 Respiratory Respiratory failure Diaphragmatic myopathy2,8 Neurological Seizures, paraesthesiae Electrolyte and/or metabolic disturbance,1,4 cellular hypoxia secondary to reduced 2,3-DPG and ATP Wernicke’s encephalopathy Thiamine deficiency1,2,13 Gastrointestinal Diarrhoea or constipation Electrolyte and/or metabolic disturbance,4 intestinal atrophy following malnutrition13 Haematological Sepsis Leukocyte dysfunction, hyperglycaemia, acid–base disturbance1,4 Haemorrhage Thrombocytopaenia,2,9 platelet dysfunction9 Haemolytic anaemia Depletion of erythrocyte ATP, resulting in increased cell membrane rigidity1 Metabolic Hyperglycaemia4 Glucose ingestion4 Acid–base disturbance1,4 Impaired phosphate renal buffering2,12 Renal Acute tubular necrosis Rhabdomyolysis4 Musculoskeletal Myopathy Depletion of muscle ATP,1,9 electrolyte disturbance1 Rhabdomyolysis Impaired production of phospholipid cell membranes causes sarcolemma dysfunction1,2 ATP = adenosine triphosphate. DPG = diphosphoglycerate.

Adrian T Fung MB BS · Janet Rimmer MB BS, MD, FRACP

Macrophagic myofasciitis is characterised by sheets of macrophages in striated muscle, a few lymphocytes and inconspicuous muscle fibre damage. It is due to aluminium contained in vaccines, and is localised to the inoculation site. We report the first Australian case, detected incidentally when investigating a raised serum creatine kinase level. Clinical record During investigations for gastroesophageal reflux, a 32-year-old man was noted to have intermittently raised serum creatine kinase levels: 78 U/L in April 2003, 484 U/L in July 2003 and 8846 U/L in August 2003 (reference range, < 196 U/L), with normal troponin levels. He had no neuromuscular symptoms and played sport regularly. A previous serum creatine kinase level of 2000 U/L had been recorded in April 2000, when he had multiple pulmonary emboli after an overseas trip. He had been given inactivated hepatitis A (Havrix) and poliomyelitis vaccines intramuscularly in March 2000, and a booster inoculation for hepatitis A in February 2001. He was taking allopurinol for renal calculi and omeprazole for reflux. His father had died from motor neurone disease and a brother had fasciculations. The patient had no evidence of muscle weakness or wasting, no fasciculations, and the remainder of his neurological examination, as well as needle electromyography, was normal. Muscle biopsy The interstitial connective tissue of the deltoid muscle contained a dense infiltrate of large macrophages (Figure A). Electron microscopy showed spiculated structures within these macrophages (Figure B). When an electron beam hits a sample it releases x-rays of wavelength specific to the elements in the sample. Using this principle, an EDAX x-ray detector revealed an aluminium peak (Kα, 1.48 keV) from the aggregates. A: Deltoid muscle biopsy. Densely packed macrophages with abundant cytoplasm (arrowhead) were seen between muscle fibres (M), together with a few peripheral lymphocytes (thin arrow). No muscle fibre necrosis, regeneration, multinucleate giant cells, Michaelis–Guttmann bodies (found in malakoplakia) or granulomas were present. The macrophages stained positively with acid phosphatase and CD68. The lymphoid population showed a mixture of T and B lymphocytes. Stains for acid-fast bacilli were negative. (Haematoxylin and eosin. Bar = 50 m.) B: Electron micrograph showing electron-dense, randomly orientated, fine spiculated structures (asterisks) within a macrophage (M) (200 nm resin sections on nickel grids examined in a Philips CM120 electron microscope. Osmium and uranyl acetate. Bar = 1 µm.) Macrophagic myofasciitis is characterised by the presence of sheets of macrophages in striated muscle, a few lymphocytes and inconspicuous muscle fibre damage. It is due to the persistence of vaccine-derived aluminium in the muscle at the injection site and the myofasciitis is localised to the injection site. Since macrophagic myofasciitis was first described in 1993,1 more than 200 cases have been identified in France, with only a few cases reported from other countries.2 This is the first case of macrophagic myofasciitis reported in Australia. Aluminium is used as an adjuvant in diphtheria – tetanus –pertus sis, some Haemophilus influenzae type b, pneumococcal, hepatitis A and B, anthrax and rabies vaccines, as well as in tetanus toxoid.3 For example, each millilitre of Havrix contains 0.5 mg of aluminium, as aluminium hydroxide. The mechanism of macrophagic myofasciitis is thought to be secondary to an ongoing local immune reaction to the long-term persistence of this aluminium in the muscle.4 Macrophagic myofasciitis commonly occurs in adulthood, although the age ranges between 1 and 70 years.5,6 The clinical picture is variable, and includes nonspecific symptoms such as myalgia, arthralgia, muscle tenderness, muscle weakness, fever and fatigue. A few patients show raised serum creatine kinase levels and myopathic electromyography.6,7 Neurological manifestations resembling multiple sclerosis have been reported in some patients,8 and rarely it is associated with other diseases such as inclusion body myositis.9 Co-existent autoimmune diseases have been recorded in some patients with macrophagic myofasciitis.10 Steroids, analgesics and antibiotics have been used in attempts to treat this condition.10 Our patient did not have any neuromuscular symptoms and the muscle biopsy was performed because of his raised serum creatine kinase level. There was no correlation between macrophagic myofasciitis and the clinical signs and symptoms in this patient, who was asymptomatic. Therefore, we consider this histological finding to be incidental in a patient with a “CKopathy”. Recently, a genetic predisposition to macrophagic myofasciitis has been suggested to account for the disparity between the low prevalence of this disorder and the widespread use of aluminium-containing vaccines, as well as the variable incidence of this condition in different populations.5 The diagnosis of macrophagic myofasciitis is important to bear in mind, as other diagnoses such as sarcoidosis, connective tissue disease, tuberculosis, Whipple’s disease and malakoplakia may be entertained. The patient could then be subjected to needless further investigations and undue anxiety. We hope this report will help increase awareness of this condition, and predict that more Australian cases will come to light in future deltoid muscle biopsies.

Meena Shingde MB BS, MD · Roger Pamphlett MD, FRACP, FRCPath · James Hughes FRACP · Ross Boadle Dip(MT), MAIMS · Edward J Wills MD, FRCPA

Since the human genome was sequenced, there has been intense activity to understand the function of the 30 000 identified genes; attention has now turned to the products of genes — proteins. Proteomics is the large-scale study of the structure and function of proteins; it includes the rapidly evolving field of disease proteomics, which aims to identify proteins involved in human disease and to understand how their expression, structure and function cause illness. Proteomics has identified proteins that offer promise as diagnostic or prognostic markers, or as therapeutic targets in a range of illnesses, including cancer, immune rejection after transplantation, and infectious diseases such as tuberculosis and malaria; it has the potential to allow patient-tailored therapy. Some major challenges remain, both technical (eg, detecting “low-abundance” proteins, and maintaining sample stability) and in data management (eg, correlating changes in proteins with disease processes).

Maria Kavallaris BAppSc, PhD · Glenn M Marshall MD, FRACP

John Young, Professor of Physiology, former Dean of Medicine and Pro-Vice Chancellor at the University of Sydney, died on 10 February 2004 of acute myeloid leukaemia. He was an exceptional scientist and a humanist with a passionate and informed interest in classical culture, Reformation theology and music. John was born on 18 April 1936 in Brisbane. He graduated from the University of Queensland with a BSc (Hons I) in pathology in 1956 and with an MB BS (Hons I) in 1960, earning the University Medal. In 1962, after an internship at Royal Brisbane Hospital, John joined the Kanematsu Memorial Institute in Sydney, where his studies on renal amino acid transport earned him an MD from the University of Queensland (1965) and a C J Martin Fellowship from the National Health and Medical Research Council. He then joined Professor Karl Ullrich at the Physiologisches Institut of the Free University in Berlin. It was Ullrich who persuaded him to work on salivary physiology, the field that John was to dominate until his death. John took up a Senior Lectureship in Physiology at the University of Sydney in late 1966, rising to become Professor of Physiology in 1976. His contributions to science were recognised by the award of a DSc from the University of Queensland (1975) and the Research Professorship of the Alexander von Humboldt Stiftung (1998). He was elected to Fellowship of the Royal Australasian College of Physicians (1976) and of the Australian Academy of Sciences (1986), in which he served as Vice President and Secretary (Biological). After he became Dean of Medicine at the University of Sydney in 1989, he oversaw the introduction of the 4-year graduate program, the development of independent clinical schools, and the foundation of the Clinical School at Canberra. Between 1994 and his retirement in 2003, he was Pro-Vice Chancellor (Health Sciences). Although he was active on many boards, including those of the Central Sydney Area Health Service and the Children’s Hospital at Westmead, he was particularly proud of his role in fostering the Menzies School of Health Research (in Darwin) and (in Sydney) the Kolling Institute at the Royal North Shore Hospital and the Anzac Institute at Concord Hospital. John was always active outside his own profession. He co-edited the University of Sydney’s Centenary book of the Faculty of Medicine and worked unstintingly for the Australian Physiological and Pharmacological Society and for Musica Viva. He also found time to write several biographies on important figures in Australian medicine for the Australian dictionary of biography. Most importantly, his passion for classical art and archaeology led him to play key roles in the University of Sydney’s Nicholson Museum concerts and in the creation and development of the Australian Institute of Archaeology at Athens. David I Cook

David I Cook

Richard X Davey Chemical Pathologist, Melbourne Health Shared Pathology Service, Western Hospital, Gordon Street, Footscray, VIC 3011. richard.daveyATwh.org.au To the Editor: In 1996, the Journal published my assessment of the scientific validity of a 1994 decision by the Australian Health Insurance Commission (HIC) to limit the Medicare rebate payment for assessment of thyroid function to thyroid-stimulating hormone level (TSH), except in certain more complex clinical conditions.1 For these, levels of TSH and of other indicators of thyroid function, such as thyroxine, are tested simultaneously and a rebate given for the group of tests. Although discussion concerning this diagnostic strategy persists,2 nearly a decade later it is appropriate to assess the outcome of this initiative. Publicly accessible HIC data3 on privately ordered, then publicly refunded, thyroid function tests in Australia for the fiscal years 1994–2002 were retrieved and are presented graphically (Box). Figure A shows the change in thyroid function test ordering sought by the HIC occurring in 1997 through to 2000 and probably now consolidating. Overall, before the initiative, there were 1.55 TSH tests ordered for each thyroid function group test, and in 2002 this increased to 2.65. The outcome in the elderly is similar, but the change is even more noticeable for thyroid testing in young women and men (with ratios of about 5 to 1 and 7 to 1, respectively). Clinicians have presumably come to accept the high negative predictive value of a normal TSH result for ruling out primary thyroid disease as both necessary and sufficient to finalise thyroid diagnoses in the young. By contrast, thyroid disorders are more common among the elderly, who thus more readily satisfy the HIC requirements for thyroid function group tests. The approximately fourfold increase in absolute terms in the number of single TSH tests performed over 9 years (from 2731 per 100 000 persons per annum in 1994 to 10 763 in 2002) can also be seen as vindicating the HIC’s decision to run with a “TSH first” testing protocol. The same pattern is seen in the age and sex groups illustrated (15–24 years and 75–84 years). The present speed, ease and relative economy of obtaining a TSH test, and the reliability, particularly at low TSH levels, of using this measure for thyroid disease case finding, make ordering a TSH test no longer an indulgence,4 but a clinical necessity. The national cost-of-living index for 30 June of each fiscal year5 was used to standardise the annual expenditure on thyroid function tests to 1994 dollar values, thus allowing comparison across the decade (Figure B). From 1995 to 2002, the HIC has contained annual expenditure to under $20 million for thyroid function group testing. This is both desirable and appropriate. That this has been sustained for 7 years in the face of increasing numbers of first-line TSH tests is both astonishing and commendable. Most of the increase in costs of TSH testing is probably explained by the acceptance of its use as a first-line test. Between the 1996 and 2001 censuses, the population grew from 17.9 to 18.8 million, and the proportion over 65 years also increased (from 12% to 12.5%). Both these trends are continuing,5 and both also explain some of the increase in ordering of TSH tests. It is unclear if any of this change is also due to testing moving from the totally public, hospital sector, not funded by the HIC, to the HIC-funded sector. Effect of changes to the Health Insurance Commission rebate for thyroid function testing A: Ratio of the number of single tests ordered (thyroid-stimulating hormone [TSH]) to the number of thyroid function group tests ordered (TSH and thyroid hormones). Data are tests per 100 000 persons per annum. B: Annual expenditure on thyroid function testing in Australia.

Richard X Davey

Jan R Stockigt Senior Endocrinologist, Alfred Hospital, Commercial Road, Prahran, VIC 3181. jrsATnetspace.net.au Comment: In his timely review of changing patterns of thyroid function testing, Davey suggests that Australian Health Insurance Commission (HIC) policy is responsible for the increased emphasis on a “TSH-first” strategy, with consequent containment of costs for other thyroid function tests. While this may in part be true, the trend towards initial TSH testing has been advocated worldwide1 following the development of TSH assays sufficiently sensitive to distinguish the typical suppressed TSH levels of thyrotoxicosis from normal levels. The developments documented by Davey are a consequence of technological development, perhaps enhanced by selective rebating as a result of HIC policy. It is unfortunate that current HIC policy is sometimes described as prohibiting more complete thyroid function testing, unless TSH level is abnormal. Rebate policy does not prohibit any line of testing and it is because the “TSH-first” approach has some serious, well-documented deficiencies.2 Measurement of levels of thyroid hormone in addition to TSH is clearly sanctioned in HIC regulations when TSH level alone can be misleading, for example in suspected pituitary dysfunction, or in monitoring the treatment of thyroid dysfunction. The adverse consequences, both human and financial, of relying on TSH measurement alone in such situations can be serious and may outweigh the savings achieved by restrictive testing. It must be noted again that a normal concentration of immunoreactive TSH has no predictive value in ruling out potentially life-threatening hypopituitarism,3 which may present with prominent hypothyroid features. The effective integration of clinical and laboratory investigation of potential thyroid dysfunction requires an active laboratory–clinical interface. There are over a dozen patterns of thyroid function — some trivial or inconvenient, some quite serious — that can be misdiagnosed or incorrectly managed if communication across this interface is inadequate.4 Effective communication requires relevant information from the clinician and a response to this information within the laboratory. It is a reality that current patterns of investigation in Australia frequently fall short of this ideal. If, as a result of automation and effective competition, the unit cost of assays can eventually be reduced in relation to the total cost of medical care, it may become appropriate to revert to a more complete panel of initial testing that integrates tropic hormone and target gland secretion, a strategy that remains the cornerstone of definitive endocrine investigation.

Jan R Stockigt

Possible protection against cancer and improved immune function make supplementation with selenium attractive, but its toxicity and other unknown effects urge caution Selenium presents a nutritional conundrum because of its dual status as a highly toxic, but essential, trace element.1 The eightfold gap between the estimated average requirement2 and the upper limit of safe intake is relatively narrow, so questions of too much and too little are important. Additional key questions pertain to adequate versus optimal status, and reflect the shift in focus of nutrition from preventing deficiency towards promoting optimal health. As is the case for many micronutrients, the quest for protective effects of selenium (Se) intakes above requirements is rapidly gaining momentum. Ever since the biological role of Se in humans was first delineated less than 30 years ago, evidence for its increasing scope and importance to human health has been rapidly accumulating. Increasingly, Se depletion, as opposed to “deficiency”, is being associated with a range of health outcomes, including viral infection, reproduction, mood, thyroid function, cardiovascular disease, inflammatory conditions, immune function and cancer protection. 3,4 It is possible to advance a range of theoretical arguments that suboptimal Se status may have an effect on health, but evidence of a direct relationship to health outcomes is very limited. Se research is incipient and there is a paucity of data. For example, Se reference values that have been adopted in the United States2 are based on only two studies, one of which was a 1983 Chinese study of poor quality. Research is hampered by substantial difficulties in assessing and interpreting Se intakes and status, which become even more significant in the context of extreme global variations in the Se content of soil, food and human tissue.3,4 We do know that Se has key roles in redox regulation and antioxidant function, and hence in membrane integrity, energy metabolism and protection against DNA damage. 1,3,4 These and other functions are mediated through over 35 selenoproteins, which require adequate Se intake for synthesis and expression. Selenoproteins include several forms of the enzymes glutathione peroxidase (GPx), thioredoxin reductase and iodothyronine 5'-deiodinase. The number of known selenoproteins has almost trebled over the past 7 years,1,3 although the roles of several remain undefined. Plasma Se concentration is the most commonly used indicator of Se status.2 Low Se intakes, plasma Se concentrations and GPx activities have direct, linear associations up to a threshold plasma Se concentration (70–100 μg/L), beyond which GPx activity plateaus. This maximum GPx concentration is thought to represent repletion, and commensurate Se intake forms the basis of recommended dietary requirements.2,5 Concentrations of other selenoproteins are also influenced by Se intake and may have a role as functional indicators of Se status, 2,3,5 but assay methods and reference standards are at an early stage, and comparisons between studies are difficult. There is differential hierarchical expression of the selenoproteins, with relative preservation of the presumably more metabolically important at lower intakes of Se. 1,3 However, we do not clearly understand the health implications of submaximal expression of the selenoproteins. There are enormous geographical variations in the Se content of soil and food, and hence in Se intakes and concentrations in human blood and tissues.3,4,6 Thus, it is essential to use local data for monitoring and interpreting Se status.6 The 2000 US Recommended Dietary Allowance (RDA) is 55 μg/day.2 The 1987 Australian RDAs are 70 μg/day for women and 85 μg/day for men, but these are currently under review.7 Organic selenomethionine is the predominant form of Se in food. The most important dietary sources of Se are meat, poultry, fish and cereals (although brazil nuts are very high in Se and certain fish also have particularly high levels). Accurate assessment of intake is exceptionally difficult because the Se content of food is so variable. 2,3,6,8 Estimates of Se intakes include 106 μg/day in a large representative US sample,2 and a range of 29–70 μg/day in Europe.3 Extremely limited Australian data suggest intakes of around 90 μg/day,6 while more comprehensive New Zealand data show intakes as low as 28 μg/day, and indicate that conventional dietary intake methods are inadequate for estimating Se intake.8 Inorganic Se (selenite and selenate) is only available through supplementation, is generally less bioavailable and produces a different physiological response than organic forms of Se. 1,2 Environmental changes and agricultural practices may be reducing Se concentrations in soil.4 These factors, in conjunction with trade barriers (eg, the cessation of importing high-Se US wheat to the European Union), appear to be associated with a decline in the availability of Se through the food chain and in human Se status, particularly in Europe.3 Changes in food supply and habits, including the importation of Australian wheat, have improved the previously marginal Se status of New Zealanders.9 Twenty-six European studies since 1990 all reported mean plasma Se concentrations below 100 μg/L, the level postulated to be required for GPx saturation and cancer protection. 3,10 Ten of these studies reported plasma Se levels under 70 μg/L,3 postulated by others to be associated with GPx saturation.11 A representative US plasma Se level was 124 μg/L.2 In this issue of the Journal (page 383), Lyons and colleagues present evidence that although mean plasma Se concentrations of South Australians are relatively high by European standards, they may be declining, and over a third of their sample had levels below 100 μg/L.12 Overt human Se deficiency is rare. It is manifested as Keshan disease, an endemic fatal cardiomyopathy, which is virtually unknown outside areas of China, where the levels of Se in soil and dietary Se intake are extremely low. A few studies have reported Se deficiency as a result of long-term total parenteral nutrition.1 Despite myriad claims for potential relationships between a range of diseases and Se status, there are no clear population health outcomes that can be attributed to Se status in countries like New Zealand, where intakes are very low. 1,9 The evidence for an effect of Se on health outcomes is strongest in cancer prevention. Secondary findings from the 10-year US Nutritional Prevention of Cancer Trial demonstrated a protective effect of supplementation with 200 μg/day of organic Se (from yeast) on total cancer incidence and mortality, and on prostrate cancer incidence (relative risk, 0.75, 0.59, and 0.48, respectively).10 The effects were stronger in men and in those with lower baseline plasma Se levels (< 105 μg/L), and were not found for a range of other site-specific cancers. Of concern is that in the top tertile for baseline plasma Se level there may be an association between supplementation and increased risk of breast cancer and melanoma, as well as overall cancer incidence.10 There are numerous limitations to what was a small study, and the relatively high baseline plasma Se levels (114 μg/L) make it difficult to generalise the findings. It appears that protection from cancer may require supplementation beyond correction of depletion and maximal expression of the selenoproteins. Several large trials are under way to clarify the benefits and risks of Se supplementation with respect to tumorigenesis. More speculative and tantalising is the potential association between Se and immune function. Evidence suggests that reduced Se status may be associated with the incidence of clinical infection in adults,13 and supplementation of apparently Se-replete individuals potentially enhances immune function.3 Animal studies indicate that the Se status of the host can genetically alter invading viral pathogens, so that a normally benign strain may become virulent in an Se-deficient host.14 This is of interest given the emergence of new influenza virus strains from China, where there are significant areas of overt Se deficiency, and given the decline in Se status associated with progression of HIV infection.3 In summary, there has been an explosion of interest in the biological role of Se and the potential health implications of Se status. Much of the evidence in humans is descriptive, and the dearth of quality prospective trials means the links with many diseases are still controversial and, in many cases, speculative. There are very limited representative data on Se content of the food supply and Se status in many populous parts of the world, and no nationally representative Australian data. Lyons and colleagues provide the most comprehensive Australian plasma Se data to date,12 but they are neither prospective nor representative, and there may be variations according to states.6 Outcomes of research on Se in the next decade are likely to be important, and we urgently need more Australian data. Meanwhile, it is necessary to remember that selenium is toxic.1-3 Intakes below 400 μg/day are considered safe for almost all individuals.2 As illustrated by the Nutritional Prevention of Cancer Trial,10 outcomes of Se supplementation are variable and may not be without risk. Benefits and an appropriate dose for supplementation remain controversial. Until further evidence is available, supplementation should be recommended with caution, and overconsumption should be avoided.3

Lynne A Daniels PhD, APD