Intact parathyroid hormone measurement at 24 hours after thyroid surgery as predictor of parathyroid function at long term

BACKGROUND: There is no consensus about the usefulness of postoperative intact parathyroid hormone (iPTH) determination to predict permanent hypoparathyroidism (pHPP). We evaluated the value of calcium (Ca2+) and iPTH concentration at 24 hours after total thyroidectomy (TT) for predicting pHPP. METHODS: Ca2+ and iPTH levels from 70 consecutive patients who underwent TT were measured at 24 hours and 6 months after TT. RESULTS: Five patients (7.1%) developed pHPP. An iPTH concentration <= 5.8 pg/mL at 24 hours after TT identified patients at risk for pHPP (sensitivity, 100%; specificity, 81.5%), but it was not accurate enough to predict its development (positive predictive value, 30%). Conversely, an iPTH level > 5.8 pg/mL predicted normal parathyroid function at 6 months (negative predictive value, 100%). Compared with iPTH, a postoperative Ca2+ level <= 1.95 mmol/L was 60% sensitive and 78.5% specific to predict pHPP. CONCLUSIONS: An iPTH concentration > 5.8 pg/mL on the first postoperative day rules out pHPP with much better diagnostic accuracy than Ca2+. Postoperative iPTH could be helpful in identifying patients at risk for developing pHPP. (C) 2013 Elsevier Inc. All rights reserved.