A Single Parathyroid Hormone Level Obtained 4 Hours after Total Thyroidectomy Predicts the Need for Postoperative Calcium Supplementation

Abstract

Parathyroid hormone (PTH) levels after total thyroidectomy have been shown to predict the development of symptomatic hypocalcemia and the need for calcium supplementation. This study aimed to determine whether a PTH level drawn 4 hours postoperatively is as effective as a level drawn on postoperative day 1 (POD1) in predicting this need. This is a single-institution retrospective review of 4-hour and POD1 PTH levels in patients who underwent total thyroidectomy from January 2012 to September 2012. If POD1 PTH was ≥10 pg/mL, patients did not routinely receive supplementation; if PTH was <10 pg/mL, patients received oral calcium with or without calcitriol. Of 77 patients, 20 (26%) had a 4-hour PTH <10 pg/mL; 18 (90%) of these patients had a POD1 PTH <10 pg/mL. No patient with a 4-hour PTH ≥10 pg/mL had a POD1 PTH <10 pg/mL. All 18 patients with POD1 PTH <10 pg/mL received calcium supplementation. Three additional patients received supplementation due to reported symptoms or surgeon preference. A 4-hour PTH ≥10 pg/mL compared with a POD1 PTH had a similar ability to predict which patients would not need calcium supplementation; sensitivity was 98% vs 98%, specificity was 90% vs 86%, and and negative predictive value was 95% vs 95%. Of 21 patients who received supplementation, 13 (62%) also received calcitriol, including 9 patients (69%) with a 4-hour PTH <6 pg/mL. A single PTH level obtained 4 hours after total thyroidectomy that is ≥10 pg/mL accurately identifies patients who do not need calcium supplementation or additional monitoring of serum calcium levels. Same-day discharge, if deemed safe, can be accomplished with or without calcium supplementation based on the 4-hour PTH level. Greater consideration should be given to calcitriol supplementation in patients with a 4-hour PTH <6 pg/mL.