Effect of preoperative vitamin D deficiency on postoperative hypocalcemia after thyroid surgery

BACKGROUND Transient post thyroidectomy hypocalcemia occurs in up to 30% of patients. We evaluated the effect of vitamin D deficiency on post thyroidectomy hypocalcaemia. METHODS This is a prospective study which was conducted from November 2010 to January 2013 and a total of 35 patients were included and data was analyzed regarding the relation between preoperative vitamin D3 levels and occurrence of post- thyroidectomy hypocalcemia. Patients were divided into two groups dependent upon the preoperative serum vitamin D level: group 1 with vitamin D levels <20 ng/ml and group 2 with serum vitamin D levels ≥20 ng/ml. Hypocalcemia was defined as a postoperative calcium level <8.5 mg/dl. RESULTS There was a difference in postoperative hypocalcemia between the two vitamin D groups. In patients with serum vitamin D ≤20 ng/ml mean pre-operative and post-operative serum calcium levels were 9.3 ± 0.5 and 8.4 ± 0.58 g dl (p < .001) whereas in patients with serum vitamin D levels >20 ng/ml mean pre-operative and post-operative serum calcium were 9.52 ± 0.64 and 8.9 ± 0.5 (p = ns). CONCLUSIONS Pre-operative serum vitamin D levels have got positive correlation with serum calcium levels in early post-operative period. Patients with serum vitamin D levels <20 ng/ml are highly likely to develop early post-operative hypocalcaemia and the difference between pre-operative and post-operative serum calcium levels in vitamin D deficient patients was significant (p < 0.001).