Graft-dependent Renal Hyperparathyroidism Despite Successful Kidney Transplantation

Introduction Only a few reports can be found on the recurrence or persistence of hyperparathyroidism after total parathyroidectomy and autotransplantation (PTX + AT) following kidney transplantation (KTX). The objective of the present study was to assess the frequency and pathophysiological mechanisms responsible for the development of graft-dependent renal hyperparathyroidism (rHPT) after KTX. Patients and methods Between 1986 and 2006, 69 patients underwent surgery for rHPT after KTX at our institution. Patients with reoperations at the parathyroid autograft (AT) were identified. Kidney graft function (KGF) was assessed by the glomerular filtration rate (GFR). Representative parts of the parathyroid gland chosen for autotransplantation during the initial parathyroidectomy and of the excised AT at reoperation were reanalyzed according to the morphologic pattern and the proliferative index. Results Eight of the 69 patients underwent reoperation of the AT. All patients had undergone initial PTX + AT before KTX. The GFR before parathyroid reoperation was 66.6 ± 9.6 ml/min per1.73 m² (mean ± SEM). Histopathological re-examination revealed nodular hyperplasia in the parathyroid tissue for autotransplantation and in the excised parathyroid autografts. The Ki67 index was increased in the glands chosen for autotransplantation prior to KTX, but was overall low in the excised autografts. Discussion Although not reported in the literature to date, tertiary hyperparathyroidism (tHPT) may arise from parathyroid autografts even in patients with a good KGF. In these cases, graft-dependent tHPT represents the inability of autonomous, nodular parathyroid tissue to regress despite the recovery of renal function. Non-nodular tissue should be selected for parathyroid autotransplantation to decrease the incidence of graft-dependent recurrent rHPT.