Pathologic Features of Parathyroid Glands Associated With the Pathogenesis of Long-lasting Persistent Hyperparathyroidism After Kidney Transplantation in Long-term Dialysis Patients

Background. Persistent hyperparathyroidism in kidney transplant recipients may be prolonged for a few years, and in these cases, parathyroidectomy is indicated even if graft function is satisfactory. The aim of this study was to characterize the parathyroid glands in long-term dialysis recipients and determine the pathogenesis of persistent hyperparathyroidism. Methods. We analyzed 44 parathyroid glands resected from 11 patients who underwent parathyroidectomy after kidney transplantation. The histopathologic types and weights of all the parathyroid glands were evaluated. Results. The mean dialysis period was 15.8 years, and the time from kidney transplantation to parathyroidectomy ranged from 3.5 to 89 months. Nodular hyperplasia was present in parathyroid glands in all cases. The mean glandular weight was 396.0 +/- 299.0 mg, and the maximum glandular weight was 3200 mg. Seven patients who underwent parathyroidectomy >1 year after kidney transplantation (late PT) were compared with 4 patients who underwent parathyroidectomy within 10 months after transplantation (early PT). The maximum (442.9 vs 1503 mg; P = .018) and mean (312.5 +/- 177.4 mg vs 1135.6 +/- 977.7 mg; P = .001) glandular weights were significantly lower in patients who underwent late PT compared with those who received early PT. Based on the histopathologic type and glandular weight of each parathyroid gland, nodular hyperplasia in glands <= 150 mg was common in patients who underwent late PT. Conclusions. The presence of nodular hyperplasia in parathyroid glands with a low weight may be involved in long-lasting persistent hyperparathyroidism in patients undergoing long-term dialysis.