Preoperative Vitamin D Deficiency Predicts Postoperative Hypocalcemia After Total Thyroidectomy

Background Transient postthyroidectomy hypocalcemia occurs in up to 30% of patients. We evaluated the effect of vitamin D deficiency on postthyroidectomy hypocalcemia. Methods Data were collected prospectively between January 2006 and March 2009. A total of 166 consecutive total thyroidectomies were analyzed regarding the relation between preoperative vitamin D 3 levels and postoperative corrected calcium levels. Patients were divided into three groups dependent upon the preoperative vitamin D 3 level: group 1, <25 nmol/l; group 2, 25–50 nmol/l; group 3, >50 nmol/l (conversion factor of 2.5× between nanomoles per liter and nanograms per milliliter). Hypocalcemia was defined as a postoperative calcium level <2.00 mmol/l (8 mg/dl). Hospital length of stay was recorded. Results There was a difference in postoperative hypocalcemia between the three vitamin D 3 groups (group 1 (32%) vs. group 2 (24%) vs. group 3 (13%). Hypocalcemia in group 1 (vit D <25 nmol/l, <10 ng/ml) was significantly more likely than in group 3 (vit D >50 nmol/l, >20 ng/ml) ( P = 0.025, χ 2 test. Vitamin D 3 deficiency was also associated with a longer hospital stay (median stay 2 days vs. 1 day, P < 0.001, Wilcoxon rank test). Conclusions There is a significant difference in postoperative hypocalcemia rates between those with vitamin D levels >50 nmol/l (>20 ng/ml) and those with a level of <25 nmol/l (<10 ng/ml). Vitamin D deficiency leads to a delay in discharge owing to a higher likelihood of hypocalcemia.