Evaluation of Vitamin D Status and its Impact on Thyroid Related Parameters in New Onset Graves' Disease- A Cross-sectional Observational Study

AIMS AND OBJECTIVE: We aimed to compare serum vitamin D level in new onset Graves' disease versus age and sex matched controls. Furthermore, we assessed the correlation of vitamin D with hormonal parameters and antibody titers in Graves' disease. MATERIALS AND METHODS: In total, 84 patients of new onset Graves' disease and 42 age and sex matched healthy individuals were recruited. Biochemical and hormonal investigations that included serum calcium, phosphorous, free triiodothyronine (FT3), free thyroxine (FT4), thyroid stimulating hormone (TSH), 25 hydroxy vitamin D (25(OH) D), and parathyroid hormone (PTH) were done for all subjects. Thyrotropin receptor antibody (TRAb) was measured only for Graves' disease patients. RESULTS: The patients with Graves' disease had significantly lower 25(OH) D levels (19.2 ± 8.9 ng/ml) as compared to control subjects (23.8 ± 12.5 ng/ml) (P = 0.019). Thyroid hormone levels, thyroid volume, and TRAb titers did not differ significantly between vitamin D deficient Graves' disease group (25(OH)D <20 ng/ml) and vitamin D non deficient Graves' disease group (25(OH)D ≥20 ng/ml). Furthermore, serum vitamin D level did not correlate significantly with thyroid hormones, thyroid volume, or TRAb titers among Graves' disease. The odds ratio (OR) for association of vitamin D deficiency (VDD) state and Graves' disease was 1.62 (95% CI 0.77–3.41). Vitamin D sufficiency state was associated significantly with lower risk of Graves' disease (OR = 0.38, 95% CI 0.15–0.95). CONCLUSION: Serum vitamin D levels are significantly lower in new onset Graves' disease. No significant correlation between vitamin D and thyroid hormones, thyroid volume, or TRAb titers was found in these patients. VDD state is not associated with Graves' disease.