Evaluation of intraoperative parathormone measurement for predicting successful surgery in patients undergoing subtotal/total parathyroidectomy due to secondary hyperparathyroidism.

Objectives/background: The aim of this study is to investigate the predictive value of intraoperative parathormone measurement addressing successful surgical resection in patients with secondary hyperparathyroidism.

Methods: The study included 42 consecutive patients operated on between May 2006 and July 2008. Patients were grouped according to successful surgery (Group 1, n = 36) and persistent postoperative hyperparathyroidism (Group 2, n = 6). Serum phosphorus (P), total calcium (tCa), ionized calcium (iCa), intact parathormone (iPTH), and alkaline phosphatase (ALP) were drawn preoperatively and intraoperatively upon 15 minutes after completion of resection (iPTH(15)). The rate of decrease of pith detected by iPTH(15) compared to preoperative values was calculated (iPTH(%)).

Results: Preoperative P, tCa, iCa, iPTH, and ALP were comparable. Subtotal parathyroidectomy (sPx) (n = 27) and total parathyroidectomy with autotransplantation (tPx) (n = 15) were performed. Mean iPTH(15) value, iPTH(%) rates were 145.9 +/- 12.3 pg/mL, % 91.6 +/- 0.7, and 522.5 +/- 85.4 pg/mL, % 75.1 +/- 2.0 (P = ,001) in Groups 1 and 2, respectively. Mean serum tCa and iCa at POD#1 in Group 1 were 7.6 +/- 0.1 mg/dL, 0.910 +/- 0.4 mmol/L, and Group 2 were 8.3 +/- 0.3 mg/dL, 1.050 +/- 0.4 mmol/L (P < .05), respectively. ALP levels were similar.

Conclusion: iPTH(15) value and iPTH(%) rate accurately predicts the completeness of resection in secondary hyperparathyroidism. The rate of decrease in serum iPTH detected intraoperatively compared to preoperative baseline levels exceeding 90% in sPx, 95% in tPx, accurately predicts the success of surgery. Postoperative normocalcemia without calcium replacement would raise a suspicion about completeness of surgical resection.