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Even asymptomatic patients should be considered for surgery
MJA 1998; 168: 148-149
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The report by Delbridge et al in this issue of the Journal1 describes the changing clinical picture of primary hyperparathyroidism (PHPT) in patients referred for surgical treatment at Royal North Shore Hospital, Sydney, over the past 30 years. The most common presentation in the 1990s is in women over the age of 50 years with bone loss indistinguishable from that of postmenopausal or senile osteoporosis (31%). Patients with kidney stones still constitute 15%, and those with subtle but distressing symptoms of fatigue, depression or altered cognitive function constitute 20%. Delbridge et al have also observed an "exponential" increase in the number of cases referred for surgery over the past decade, reflecting contemporary epidemiological studies which have unearthed a virtual epidemic of PHPT among postmenopausal women -- it affects 2% to 3% of women in this age group.2,3 Even so, the absolute number of patients undergoing operation at Royal North Shore Hospital each year remains small when compared with the number expected by extrapolation from this prevalence. Presumably, this is due in part to underdiagnosis of PHPT, as well as continuing reluctance among physicians to refer patients for surgery unless they have marked hypercalcaemia or overt "bone or stone" disease. Modern surgical treatment of PHPT is very safe, with a hospital stay of two days or less. As documented by Delbridge et al, a primary neck exploration for PHPT by experienced surgeons is successful in 95% to 98% of cases. Most authorities would agree with these authors that preoperative tumour-localising studies are not cost effective because of the significant number of both false positive and false negative results.4 The limitations of these tests are not universally appreciated by physicians, many of whom still consider a positive tumour-localising study to be a prerequisite for surgical referral. In an attempt to discourage this, John Doppman (Chief, Department of Diagnostic Radiology, United States National Institutes of Health [NIH]) stated at the NIH Consensus Development Conference on PHPT that "the only localisation study needed by a patient undergoing initial parathyroid surgery is to locate an experienced parathyroid surgeon".5 A parathyroid neck exploration is often so easy that the uninitiated surgeon may wonder what all the fuss is about. However, the operation has many potential pitfalls which can lead to failure, with the result that the patient then has to undergo further irksome and costly investigations and a potentially hazardous reoperation. There is thus a high premium on succeeding at the first try. In this regard there is no substitute for experience on the part of the surgeon, who must be able to recognise a parathyroid gland, know the distribution of the glands, where they can be hidden, and how to distinguish between normal and abnormal glands with the naked eye. To acquire this expertise requires a dedicated training in a specialised centre by an experienced preceptor.4 Which patients with PHPT should have surgery? The NIH Consensus Development Conference agreed on criteria for surgery in patients with PHPT.5 These include any one of the following:
The recent demonstration by Silverberg et al6 that parathyroidectomy markedly improves cancellous (ie, lumbar spine) bone density in patients with PHPT has added vertebral osteopenia to the list of indications for surgery. There is also increasing evidence, including a recent prospective case-control study,7 attesting to the beneficial effect of parathyroidectomy on symptoms of hypercalcaemia, such as muscle weakness, fatigue, lethargy, depression, and memory loss. Patients with such symptoms now comprise 20% of those undergoing surgery for PHPT at Royal North Shore Hospital. As for patients who are truly asymptomatic with uncomplicated (or "biochemical") PHPT, the NIH Consensus Development Conference concluded that such patients should also be considered for surgery.5 The natural history of biochemical PHPT is unpredictable, and the costs of long term surveillance are not inconsiderable.8 Given the safety and efficacy of modern parathyroid surgery, it presents an attractive alternative to indefinite follow-up. The trend toward liberalising the indications for surgical treatment of PHPT has been given added impetus recently by several Scandinavian population-based studies indicating that patients with untreated PHPT have an increased risk of dying from cardiovascular disease and malignancy when compared with age- and sex-matched controls in the normal population.9 This increased risk of death can be reduced, if not eliminated, by parathyroid surgery.10 In this context, it is particularly relevant that the earlier the disease is recognised the more rapidly the mortality risk returns to normal after surgery. What is the future of parathyroid surgery? Delbridge et al have described the latest enthusiasm for endoscopic parathyroidectomy as "a passing interest", but this may be prematurely dismissive. Rightly or wrongly, endoscopic parathyroidectomy is already being done, and workshops teaching the technique are now conducted regularly at more than one European centre. In my opinion, it would be unfortunate if this procedure were to become the province of self-proclaimed "experts" in endosurgery who have little experience of the vagaries and nuances of parathyroid anatomy and pathology -- they could have difficulty in exploring the neck if the parathyroid tumour is not found endoscopically and conversion to open operation is required. Theoretically, endoscopic parathyroid surgery may offer advantages to patients through less postoperative pain, shorter hospital stay and smaller, more aesthetically pleasing scars. It is therefore appropriate to evaluate critically the efficacy, safety and cost of this procedure relative to those of a competently performed open parathyroidectomy, by way of a prospective controlled trial.11 Anthony J Edis
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© 1998 Medical Journal of Australia.
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