Is Decline Rate of Intact Parathyroid Hormone Level a Reliable Criterion for Early Discharge of Patients after Total Thyroidectomy?

INTRODUCTION Parathyroid dysfunction leading to symptomatic hypocalcemia is not uncommon following a total thyroidectomy and is often associated with significant patient morbidity and a prolonged hospital stay. The current study aimed at evaluating the comparative predictive role of serum calcium and intact parathyroid hormone (iPTH) for post-thyroidectomy hypocalcemia. MATERIALS AND METHODS This prospective study was performed in 83 consecutive patients undergoing total thyroidectomy. Laboratory data such as serum calcium, vitamin D level, serum iPTH and serum phosphorus levels before surgery, postoperative calcium, and PTH levels measured after 1 and 6 hours and on the first postoperative day (1POD) were recorded. RESULTS Among the 83 patients, the mean (SD) age was 45.87 (12.57) years (range, 21-72 years); 70 (84.3%) patients were female. Final pathology was benign for 47 (56.6%) patients and malignant for 36 (43.4%) patients. In total, lymph node dissections were performed in 19 subjects (22.9%). On histological examination of the specimens, the parathyroid gland was found to have been removed inadvertently in 13 (15.7%) cases. In total, 35 (40.9%) patients developed hypocalcemia after thyroidectomy; receiver operating characteristic (ROC) analysis showed that a cut-off value of 15.39 pg/ml for iPTH, with a decline rate of 73% 1 hour after thyroidectomy is a significant predictor of hypocalcemia (area under the curve [AUC], 0.878; 95% confidence interval [CI], 0.79-0.96, P<0.0001) compared with calcium <8 mg/dl (2 mmol/L) with AUC=0.639; 95% CI, 0.51-0.76); P=0.067). CONCLUSION The current study showed that the decline rate in iPTH is a more reliable factor for hypocalcemia after total thyroidectomy than serum calcium. Patients with a decline rate <73% in iPTH could be discharged at 1POD without supplementation.