Objective: Postoperative iPTH assay may predict significant hypocalcemia after thyroid surgery. The present study aimed to evaluate the ability of iPTH assay to monitor parathyroid function and to identify the risk of postoperative hypocalcemia in patients underwent thyroid surgery.
Materials and methods: One hundred patients participated in the study (7 male and 93 female). Hypocalcemia was defined as a serum calcium concentration less than 8.0 mg/dL and symptoms of hypocalcemia. Concomitant serum calcium and iPTH levels were measured before operation and at 1(st) h for iPTH, 24(th) h for calcium after thyroidectomy.
Results: Postoperative hypocalcemia was observed in 31 patients. The mean postoperative serum calcium concentration in normocalcemic patients was 8.8 ± 0.5 mg/dL, whereas it was 7.6 ± 0.3 mg/dL in hypocalcemic patients. The mean postoperative 1(st) hour iPTH of patients in the hypocalcemia group was 9.1 ± 4.9 pg/mL, whereas patients of the normocalcemia group had a mean postoperative iPTH of 35.8 ± 20.2 pg/mL.
Conclusion: Postoperative 1(st) hour iPTH < 8 pg/mL with drop in iPTH level ≥ 81.5% together showed the highest diagnostic accuracy in predicting postoperative hypocalcemia.
Keywords: Hypocalcemia; intact parathyroid hormone; thyroid surgery.