SUMMARY A 65-year-old woman with a history of a left heminephrectomy for renal carcinoma developed hypercalcaemia 11 years after the operation. The same kidney was found to contain a recurrent renal carcinoma. After the radical nephrectomy of the left kidney, hypercalcaemia remitted but reappeared 11 months later. The right kidney was small but functioned at a level of creatinine clearance of 10-15 ml/min. Metastatic work-up was negative, and secondary causes of hypercalcaemia were excluded. A neck exploration revealed a parathyroid adenoma. With parathyroid resection the serum calcium declined to normal, and the risk of hypercalcaemic nephropathy in the remaining kidney was precluded.Hypercalcaemia is a common manifestation of malignancy of numerous organs, including the kidney (Albright and Reifenstein, 1948;Connor et al., 1956;Plimpton and Gellhorn, 1956;Gold and Shnider, 1959;Lucas, 1960; David et al., 1963; Noenickx et al., 1962;Moses and Spencer, 1963;Samuelsson and Werner, 1963;Goldberg et al., 1964). Primary hyperparathyroidism is a relatively common disorder, usually benign, with a frequency of 1 case per 1000 persons per year. The most common manifestation of this disorder is hypercalcaemia (Thorn et al., 1977). The association of renal carcinoma and hyperparathyroidism in the same patient is uncommon and has rarely been diagnosed before the death of the patient (Bernstein et al., 1965;Salama et al., 1971;Nemoto et al., 1977).This report describes a patient with chronic renal failure, who had had a total left nephrectomy for a recurrent renal carcinoma accompanied by hypercalcaemia and, 11 months later, was found to have recurrent hypercalcaemia. The recurrent hypercalcaemia was not due to recurrent renal carcinoma but rather to a parathyroid adenoma. After removal of a parathyroid adenoma the hypercalcaemia remitted.Received for publication 5 September 1978 Case reportThe patient is a woman who was found to have a carcinoma of the left kidney during evaluation of vaginal prolapse in 1965 at age 54. The physical examination was normal except for obvious vaginal prolapse. The full blood count, urine analysis, serum electrolytes, serum calcium and phosphate, and creatinine clearance were normal. She underwent segmental resection of the left kidney (Fig. 1). On microscopic examination the tumour was a renal carcinoma. There were no metastases nor was there evidence of local invasion. At the time of the operation the patient was described as being quite 'irritable' by several physicians. She was discharged from hospital and followed with yearly intravenous pyelograms.In July 1976, 11 years after the first operation, she was found to have progressive dilatation and clubbing of upper pole calyces, and an angiogram (Fig. 2) showed a 7 x 4 x 5 cm tumour mass involving one-half to two-thirds of the upper pole of the left kidney. The right kidney appeared to be small but without gross tumour involvement. Investigation revealed that the haemoglobin was 12-0 g/dl, WBC 7-8 x 109/l with a normal differential. T...