Assessment of Preoperative Serum Vitamin D Levels in Differentiated Thyroid Cancer

With the rising incidence of differentiated thyroid cancer (DTC), identifying its risk factors has become increasingly important. Vitamin D deficiency (VDD) is a recognized risk factor for several other types of cancer.

This study aims to assess the association between preoperative serum 25-hydroxyvitamin D (25(OH)D) levels and DTC and, secondarily, to evaluate the association between vitamin D (VIT D) supplementation and DTC.

This retrospective case-control study included patients who underwent thyroidectomy at a tertiary care institute from January 2016 to January 2022. Preoperative serum 25(OH)D levels and histopathology of the resected thyroid were evaluated. Multivariable logistic regression analysis was performed to determine the association between serum 25(OH)D levels and DTC.

A total of 633 patients were included (mean age, 46.83 ± 13.8 years; 530 (83.7%) were female), comprising 325 patients with malignant thyroid nodules and 308 patients with benign thyroid nodules who served as controls. The malignant group had significantly higher serum 25(OH)D levels than the controls (p = 0.037). However, 25(OH)D categories (deficient, inadequate, normal, and high) did not differ significantly between groups. Patients taking VIT D supplements were less likely to have DTC than those not taking supplements (45.5% vs. 57.5%, p = 0.003). In multivariable regression analysis, patients who took VIT D supplements had 37% lower odds of DTC (OR = 0.634; 95% CI = 0.460-0.873).

Serum 25(OH)D levels were not significantly associated with DTC. However, VIT D supplementation was independently associated with lower odds of DTC.