Correlation of vitamin D level with thyroid status and TSH antibody titers in patients with Graves’ disease

Abstract

Background. Various studies have shown the association of vitamin D deficiency with autoimmune diseases. Studies have found that vitamin D levels in patients with autoimmune thyroid diseases including Graves’ disease were lower than that in patients with non-autoimmune thyroid diseases such as toxic nodular goiter. Some studies have reported no such relationship between vitamin D level and autoimmune thyroid di­seases. The purpose of the study: to compare serum vitamin D level in patients with Graves’ disease versus age and sex matched controls, to assess the correlation of vitamin D with thyroid status and thyrotropin receptor antibody titers. Materials and methods. 48 patients with Graves’ disease and 24 age and sex matched healthy individuals were recruited. Hormonal investigations that included serum thyroid stimulating hormone (TSH), free thyroxine (fT4), free triiodothyronine (fT3), as well as calcium, 25-hydroxyvitamin D (25(OH)D), parathyroid hormone (PTH), thyroid stimulating hormone receptor antibody (TSH-Ab) were done for all subjects. Results. The patients with Graves’ disease had significantly lower 25(OH)D levels (16.3 ± 1.4 ng/ml) as compared to control subjects (22.8 ± 1.6 ng/ml) (p = 0.024). TSH levels and TSH-Ab titers differed 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). Thyroid volume did not differ significantly between these groups. Serum vitamin D level correlated significantly with TSH and TSH-Ab titers in patients with Graves’ disease. Conclusions. Serum vitamin D levels are significantly lower in patients with Graves’ disease. Significant correlation between vitamin D and TSH and TSH-Ab titers was found in these patients.

Keywords

• graves’ disease
• vitamin d
• tsh-ab titers