A 66-year-old woman on peritoneal dialysis for end-stage renal disease secondary to diabetic nephropathy was admitted on Christmas Day with suspected osteomyelitis of her left third toe. During admission, she complained of constipation and mild abdominal pain. There were no focal abdominal findings on examination. Of note, she was prescribed 750 mg three times daily of the rare metal lanthanum carbonate hydrate for hyperphosphataemia of renal failure. An abdominal x-ray was taken after the second dose of the day (Figure).
Lanthanum has been shown to be radio-opaque on x-ray1,2 and computed tomography,3 and this is briefly mentioned in the full product information. The radiology report in this case suggested alternative diagnoses of residual contrast from a barium study, sclerosing peritonitis, tuberculosis or lead ingestion, none of which were consistent with the clinical history.
The use of lanthanum as a phosphate binder is likely to increase since it was listed on the Pharmaceutical Benefits Schedule in 2009. Awareness of its radio-opaque features will prevent unnecessary investigations.
- 1. Cerny S, Kunzendorf U. Radiographic appearance of lanthanum. N Engl J Med 2006; 355: 1160.
- 2. Chuang CL, Chiou SY, Li SY, et al. The case: a peritoneal dialysis patient with an unusual abdominal film. Treatment with lanthanum carbonate. Kidney Int 2007; 72: 1291-1292.
- 3. Kato A, Takita T, Furuhashi M. Accumulation of lanthanum carbonate in the digestive tracts. Clin Exp Nephrol 2010; 14: 100-101.
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