[Evaluation of parathyroid function in presternal subcutaneous grafting after total parathyroidectomy for renal hyperparathyroidism].

INTRODUCTION

In the setting of total parathyroidectomy (TPT) and parathyroid transplantation (PTx) for renal hyperparathyroidism (RHP), we evaluated long-term parathyroid graft function after subcutaneous presternal transplantation (SCPTx).

HYPOTHESIS

Parathyroid glands are surrounded by fatty tissue. Therefore, we postulated that subcutaneous implantation of parathyroid tissue after TPT for RHP could be at least as effective as intramuscular grafting and would avoid the complications of the latter technique.

MATERIAL AND METHOD

We performed a study in a university hospital and its dialysis unit.

DESIGN

Prospective open efficacy study of a postoperative diagnostic monitoring method of intact parathyroid hormone (iPTH) in a cohort of surgical patients without loss to follow-up.

PATIENTS AND INTERVENTIONS

Thirty-five patients (19 women and 16 men) underwent TPT and SCPTx for RHP at the Department of General Surgery and Department of Nephrology, Donostia Hospital, San Sebastián, Gipuzkoa, Spain, from January 2002 to December 2005. Follow-up ranged from 6 to 42 months (mean, 15.4 months). Graft function was evaluated by measurement of plasma iPTH levels before surgery and 24 hours and 1, 3, 5, 15, 30, 60, 100 and 150 weeks after surgery. Reference values for PTH in our laboratory were 20-65 pg/mL.

RESULTS

The mean preoperative iPTH values were 1245 +/- 367.9 pg/mL (mean +/- SD) (range, 493-2160). After TPT and SCPTx, iPTH levels became undetectable in all patients at 24 hours. A value of 50 pg/mL was established as the criterion for adequate parathyroid graft function. The following values were obtained: 15.54 +/- 10.61 pg/mL (mean +/- SD) (range, 6-44) after 1 week, 57.2 +/- 1.9 pg/mL (mean +/- SD) (range, 43-74) after 5 weeks, 64.21 +/- 9.73 pg/mL (mean +/- SD) (range, 11.3-89) after 15 weeks, 75.12 +/- 9.05 pg/mL (mean +/- SD) (range, 24.6-104.2) after 30 weeks, 101.63 +/- 19.85 pg/mL (mean +/- SD) (range, 65-143) after 60 weeks, 121.63 +/- 27.85 pg/mL (mean +/- SD) (range, 62-179) after 100 weeks, 63 +/- 19.85 pg/mL (mean +/- SD) (range, 68-723) after 150 weeks and 102 +/- 18.65 pg/mL (mean +/- SD) (range, 68-113) after 200 weeks. The prevalence of hypoparathyroidism (serum iPTH level of < 20 pg/mL with a normal or low serum calcium concentration) was 2 out of 35 patients (5.71%) by week 60, with recovery of normal values by week 100. Graft-related recurrence occurred in one out of 35 patients (2.85%).

CONCLUSIONS

SCPTx after TPT and PTx for secondary RHP is an adequate method to replace muscular forearm parathyroid transplantation and avoid its complications. The functional results of TPT and SCPTx compare favorably with published data on other surgical techniques proposed for the treatment of RHP. Long-term follow-up of this series is currently being performed.