Clinicopathological analysis of persistent hypercalcemia and hyperparathyroidism after kidney transplantation in long-term dialysis patients.

Deceased donor kidney transplantation in long-term dialysis patients in Japan has been increasing because of a severe lack of donors. Parathyroid glands of long-term dialysis patients often show qualitative morphological changes from diffuse to nodular hyperplasia. Only a few studies have reported the clinicopathological analysis of persistent hyperparathyroidism after kidney transplantation in long-term (>10 years) dialysis patients. This study on consecutive deceased donor kidney transplantation performed from 2002 to 2010 measured biochemical parameters related to bone and mineral disorders and examined parathyroid tissues in parathyroidectomy cases. Thirty-four subjects (22 males; mean age, 53.8 ± 7.9 years; mean dialysis period, 14.4 ± 4.3 years) were enrolled. Multivariate analysis of potential predictors for the hypercalcemia group at 12 months after transplantation showed that pre-transplantation and early post-transplantation calcium and parathyroid hormone levels were significant determinants. Pathological examination showed that a number of glands showed nodular hyperplasia, even in small glands weighing < 100 mg. In long-term dialysis patients, hyperparathyroidism and hypercalcemia developed at an early stage after transplantation and persisted for a long period (>4 years), with nodular hyperplasia being found even in low-weight parathyroid glands. Pre-transplant high calcium and parathyroid hormone levels were the predictors for the prolonged hypercalcemia. Persistent hyperparathyroidism was considered to be caused by remaining nodular hyperplasia, even if the glands were small. Although the best treatment option is to perform a parathyroidectomy in the waiting period before transplantation, we suggest that it be performed in cases with prolonged hypercalcemia of >6 months after transplantation.