Vitamin D and risk of postoperative hypocalcemia after total thyroidectomy

Transient hypocalcemia is a well-recognized occurrence after total thyroidectomy. It has been hypothesized that underlying vitamin D deficiency may increase the risk of this complication, although to date there are few data in the literature supporting this hypothesis.

To investigate whether perioperative vitamin D levels have any effect on postthyroidectomy hypocalcemia.

We performed a retrospective review of a prospectively maintained database of thyroidectomies from November 1, 2009, through September 30, 2012, at an academic teaching hospital. The study included 121 patients with available vitamin D levels undergoing total or completion thyroidectomy. Patients with preexisting hypercalcemia or hyperparathyroidism were excluded.

All patients underwent total removal of all thyroid tissue by a capsular dissection technique. Routine calcium or vitamin D supplementation was not administered. Biochemical hypocalcemia was defined as any single postoperative corrected calcium level less than 8.0 mg/dL (to convert to millimoles per liter, multiply by 0.25) and symptomatic hypocalcemia as any symptoms of hypocalcemia.

Outcome measures were incidence of postoperative hypocalcemia and association with vitamin D levels. A multivariate analysis was performed to study the effect of other variables, including performance of central neck dissection, incidental parathyroidectomy, and hyperthyroidism, on the incidence of postoperative hypocalcemia.

The incidence of transient biochemical hypocalcemia was 24% (n = 29/121). There was no correlation between vitamin D levels and risk of postoperative hypocalcemia. On univariate analysis, performance of concomitant central compartment neck dissection revealed an increased risk of hypocalcemia (P = .06), but this finding was not significant on multivariate analysis.

Vitamin D levels do not appear to have a significant effect on the risk of postthyroidectomy hypocalcemia.