Vitamin D Status as a Predictor of Postoperative Hypocalcemia after Thyroidectomy

Abstract

Objective To determine whether perioperative vitamin D levels are predictive of postoperative hypocalcemia in patients receiving thyroidectomy. Study Design Single center retrospective study. Subjects and Methods This study included all patients receiving total or completion thyroidectomy between January 2007 and March 2017 at a single tertiary care hospital. 25-Hydroxyvitamin D (25[OH]D) levels were measured within 42 days prior to surgery or 1 day postoperatively. Hypocalcemia was defined as an adjusted serum calcium <8.0 mg/dL (based on albumin levels) or symptomatic hypocalcemia. Univariate analysis was performed with a 2-sample t test and chi-square test, while multivariate analysis was performed with logistic regression analysis to determine whether perioperative 25(OH)D level is a predictor of postoperative hypocalcemia. Results A total of 517 subjects were included in the study, 15.7% (n = 81) of whom experienced postoperative hypocalcemia with a mean ± SD serum calcium level of 7.6 ± 0.5 mg/dL as compared with 8.9 ± 0.5 mg/dL in the normocalcemic population ( P < .01). The mean 25(OH)D level for patients with hypocalcemia was 24.4 ± 12.0 ng/mL as compared with 27.5 ± 12.2 ng/mL in patients with normocalcemia ( P = .038). Subjects who were hypocalcemic experienced a significantly longer hospital stay (2.9 ± 2.5 vs 1.4 ± 1.1 days, P < .01). After adjusting for preoperative calcium, age, and performance of a neck dissection, subjects with a 25(OH)D level <30 ng/mL were significantly associated with postoperative hypocalcemia (odds ratio, 1.9; P = .041; 95% CI, 1.0-3.3). Conclusion Using a single-center retrospective study design, we demonstrated that 25(OH)D level is a significant predictor of postoperative hypocalcemia after thyroidectomy.