Tertiary hyperparathyroidism after renal transplantation: operative indications.

A retrospective analysis of our renal transplant population between 1981 and 1987 was undertaken to study the natural history of posttransplant hypercalcemia and to review indications and recommendations regarding the timing of parathyroidectomy. During this period, 1158 renal transplant procedures were performed in 1025 patients, with 819 allografts (71%) functioning currently. Posttransplant hypercalcemia greater than 10.5 mg/dl was associated with a longer duration of dialysis and developed in 227 patients, with onset of hypercalcemia occurring in 90% of these patients by 1 year. In 69% of these patients, spontaneous resolution of the hypercalcemia occurred between 6 months and 7 years after transplantation. A total of 42 patients with asymptomatic hypercalcemia are currently being followed up, with a mean serum calcium level of 11.0 +/- 0.41 mg/dl and a mean follow-up interval of 3.3 +/- 1.6 years since transplantation. Nine symptom-free patients with moderate hypercalcemia (12.0 to 12.4 mg/dl) more than 1 year after transplantation were identified. Five of these patients had spontaneous resolution of the hypercalcemia between 2 and 7 years. Fifteen patients with posttransplant hyperparathyroidism (6.6%) required parathyroidectomy--11 for symptomatic and four for asymptomatic hyperparathyroidism. One patient had symptomatic hyperparathyroidism despite the presence of normocalcemia. One symptom-free patient with significant hypercalcemia (serum calcium level, 14.7 mg/dl) underwent parathyroidectomy 3 months after transplantation. The remaining three symptom-free patients had serum calcium determinations of greater than or equal to 12.5 mg/dl more than 1 year after renal transplantation. Patients with pretransplant and posttransplant hypercalcemia required parathyroidectomy more frequently than did patients with only posttransplant hypercalcemia (18% versus 3.0%; p less than 0.001). An unusual finding was the occurrence of a single adenoma in two patients, which represents sporadic primary hyperparathyroidism in the patient undergoing renal transplantation rather than tertiary hyperparathyroidism. We recommend a conservative approach to posttransplant hypercalcemia, with surgery reserved for patients with symptomatic disease and patients with asymptomatic persistent hypercalcemia greater than or equal to 12.5 mg/dl more than 1 year after transplantation.