Preoperative vitamin D deficiency predicts postoperative hypocalcemia after total thyroidectomy

Transient postthyroidectomy hypocalcemia occurs in up to 30% of patients. We evaluated the effect of vitamin D deficiency on postthyroidectomy hypocalcemia.

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 D3 levels and postoperative corrected calcium levels. Patients were divided into three groups dependent upon the preoperative vitamin D3 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.

There was a difference in postoperative hypocalcemia between the three vitamin D3 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, χ2 test. Vitamin D3 deficiency was also associated with a longer hospital stay (median stay 2 days vs. 1 day, P<0.001, Wilcoxon rank test).

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.