Threshold-dependent risk of postoperative hypocalcemia in vitamin D-deficient patients undergoing total thyroidectomy: A meta-analysis

Background: Vitamin D deficiency is common and asymptomatic in many populations, and research reveals an association between vitamin D levels and postoperative hypocalcemia after total thyroidectomy. However, the definition of vitamin D deficiency has varied, and the threshold used might have a major impact on clinical results. The purpose of this study was to investigate the threshold effect in the relationship between vitamin D deficiency and the incidence of postoperative hypocalcemia. Methods: A meta-analysis was done following Preferred Reporting Items for Systematic reviews and Meta-Analyses recommendations. Studies that examined preoperative vitamin D levels and assessed postoperative hypocalcemia in total thyroidectomy patients were included. The investigation explored 3 vitamin D insufficiency thresholds: 15, 20, and 30 ng/mL. Odds ratios for biochemical and clinical hypocalcemia were determined, and sensitivity analyses were conducted to ensure the findings were robust. The methodologic quality was assessed using the Quality In Prognosis Studies technique. Results: Twenty-eight studies were included, with 4,944 patients, 80.4% of whom were female. The risk of having postoperative biochemical hypocalcemia was highest at the 15 ng/mL threshold (odds ratio 3.22, 95% confidence interval 1.69-6.12), and reduced as the threshold increased to 20 ng/mL (odds ratio 1.69, 95% confidence interval 1.17-2.45) and 30 ng/mL (odds ratio 1.87, 95% confidence interval 1.20-2.91). Similar patterns were seen in clinical hypocalcemia. Conclusion: This investigation demonstrates the existence of a threshold effect in the relationship between vitamin D deficiency and postoperative hypocalcemia after total thyroidectomy. The classification of vitamin D deficiency has a substantial impact on clinical outcomes, highlighting the significance of standardizing criteria to enhance preoperative treatment and patient care. (c) 2025 Elsevier Inc. All rights are reserved, including those for text and data mining, AI training, and similar technologies.