The effect of vitamin D deficiency on the risk of postoperative hypocalcemia in patients undergoing total thyroidectomy

Aim: Hypocalcemia is the most common complication following thyroid surgeries. This study aims to investigate the relationship between preoperative serum vitamin D levels and the development of hypocalcemia after bilateral total thyroidectomy operations. Materials and Methods: In this prospective clinical study, 100 patients who underwent bilateral total thyroidectomy operation at the Department of General Surgery, Harran University Faculty of Medicine, between June 2023 and September 2024 were included. The study population composed of patients diagnosed with multinodular goiter, Graves' disease, plunging goiter, or/and thyroid carcinoma not requiring neck lymph node dissection. Patients were categorized into two groups based on their preoperative vitamin D levels. Group 1 (n = 58) included patients with preoperative 25-OH vitamin D levels ≤20 ng/ml, while Group 2 (n = 42) consisted of patients with levels>20 ng/ml. The groups were compared in terms of age, gender, preoperative and postoperative corrected serum calcium levels, rates of symptomatic hypocalcemia, and PTH levels. Results: The relationship between preoperative vitamin D levels and the risk of postoperative hypocalcemia was evaluated in 100 patients who underwent total thyroidectomy. Symptomatic hypocalcemia was observed in 27 of 58 patients (46.6%) with preoperative vitamin D levels<20 ng/ml and in 4 of 42 patients (9.5%) with levels ≥20 ng/ml (p<0.001). XIII A more pronounced postoperative decline in calcium levels was noted in the group with low preoperative vitamin D levels (p<0.001). ROC analysis identified a vitamin D cutoff value of 16.5 ng/ml as predictive of hypocalcemia risk, with a sensitivity of 66.7% and specificity of 71.0% (p=0.001) . Conclusion: These findings suggest that providing vitamin D supplementation to patients with low preoperative vitamin D levels may help reduce the risk of postoperative hypocalcemia following total thyroidectomy operations. Keywords: hypocalcemia, parathyroid hormone,parathyroid gland,total thyroidectomy, vitamin D