Persistent hyperparathyroidism after kidney transplantation requiring parathyroidectomy.

INTRODUCTION

Successful kidney transplantation (KT) is believed to cure secondary hyperparathyroidism, but persistent disease has emerged in a significant number of allograft recipients. Parathyroidectomy (PTX) is ultimately required in some of these patients.

AIM

To provide an in-depth analysis of 42 patients who required surgical treatment for persistent hyperparathyroidism after successful renal transplantation and to identify risk factors for PTX present at the time of transplantation.

DESIGN

Retrospective case controlled study.

METHODS

Charts of 1332 kidney allograft recipients, transplanted between 1989 and 2000, were reviewed. Patients requiring a PTX after a first successful kidney transplantation (serum creatinine < 2.5 mg/dl) were identified. Their charts were checked for various demographic, clinical and biochemical variables. The data were compared with data obtained from a control group closely matched for time of transplantation.

RESULTS

Persistent hyperparathyroidism after successful KT requiring PTX occurred in 55 (4.1%) patients. Because of insufficient follow-up data only 42 recipients were eligible for further analysis. The age of the patients was 52 +/- 2.1 years (mean +/- SEM). The time between transplantation and PTX was 416 +/- 61 days. The mean serum creatinine at the time of PTX amounted to 1.6 +/- 0.1 mg/dl. Persistent hypercalcemia, albeit asymptomatic in most patients, was the main indication for PTX. Enlarged parathyroid glands were visualised by ultrasonography in 74% of the cases. Subtotal parathyroidectomy was the procedure of choice. The operative morbidity was negligible and the incidence of persistent or recurrent hyperparathyroidism was low, being 15%. In comparison to the control group, the patients with persistent hyperparathyroidism had a significant longer duration of pre-transplantation dialysis treatment (36.3 vs. 23.0 months, p < 0.01) and significant higher values of intact parathyroid hormone (iPTH) (268.1 vs. 96.0 ng/l, p < 0.001), total serum calcium (10.6 vs. 9.4 mg/dl, p < 0.001), and serum alkaline phosphatases (185.5 vs. 132.0 U/L, p < 0.001) at the time of transplantation. No relationship with the mode of dialysis treatment was observed.

CONCLUSION

Persistent hyperparathyroidism requiring PTX after successful KT is a common clinical problem. Patients who spent a long time on dialysis and/or patients with a high pre-transplant level of iPTH, serum calcium and alkaline phosphatases are especially at risk.