Parathyroid function in long-term renal transplant patients: importance of pre-transplant PTH concentrations

Lack of resolution of hyperparathyroidism after long-term renal transplantation is common. The relative roles of the graft function attained and the degree of pre-transplant hyperparathyroidism have not been established. Intact parathyroid hormone (iPTH) and several clinical parameters were studied before and 68.6 +/- 26.8 months (range: 30-124) after renal transplantation in 62 patients (20 females/42 males) with good renal function (creatinine <2 mg/dl). iPTH decreased from 214 +/- 229 pre-transplantion to 116 +/- 70 pg/ml post-transplantation (P < 0.01). However, only 22.6% of patients had PTH concentrations in the normal range, and values greater than twice the upper normal limit were not uncommon (27.4%). Of the many variables analysed, creatinine (r. = 0.43; P = 0.001) and pre-transplant PTH (r = 0.31; P = 0.02) significantly correlated with post-transplant PTH. After selecting patients with serum creatinine <1.5 mg/dl (n = 46), pre-transplant PTH emerged as the more important predictor of post-transplant PTH (r = 0.58; P < 0.0001). After controlling for creatinine, the partial correlation was r = 0.53, P < 0.0001. We concluded that spontaneous resolution of hyperparathyroidism after renal transplantation is uncommon. In addition, the magnitude of pre-transplant hyperparathyroidism and the renal function determine the long-term post-transplant parathyroid function.