The Role of Vitamin D Receptor and 25(OH) Vitamin D in Hypothyroidism: Insights from A South Indian Case-Control Study

Background: Thyroid hormone disorders are among the most prevalent diseases, significantly impacting public health in India and worldwide. Vitamin D has been associated with modulating thyroid neoplastic and autoimmune diseases, with the vitamin D receptor (VDR) acting as the primary receptor for vitamin D3. Aim: This study aims to investigate the role of the Vitamin D receptor (VDR) and 25-hydroxyvitamin D (25(OH)D) levels in the pathophysiology of hypothyroidism by exploring their association in a South Indian population through a case-control design. Methods: An observational study was conducted using a cross-sectional design involving 216 participants (108 hypothyroid and 108 healthy controls), aged 18-70, who were matched for age and sex. Participants with a history of thyroidectomy, pregnant women, and individuals under 18 years were excluded. Blood samples were collected from all participants for necessary investigations. Thyroid profiles, thyroid antibodies, and Vitamin D levels were assessed using a fully automated chemiluminescent hormone analyzer, and VDR levels were measured using a commercially available human ELISA kit. All biochemical parameters were analyzed using a fully automated biochemistry analyzer. A p-value of <0.05 was considered statistically significant. Results: The VDR levels among cases and controls were 0.72 ± 0.30 and 2.26 ± 0.97, and 25(OH) D3 levels were 17.04 ± 6.03 & 22.09 ± 9.75, respectively. A statistically significant difference in VDR and 25(OH) D3 levels was found between the case and control groups (p < 0.05). Conclusions: Our findings indicate that serum VDR levels are significantly lower in patients with thyroid abnormalities than in healthy controls, suggesting that VDR may serve as a diagnostic marker for thyroid dysfunction.