The association between serum 25OHD levels and hypothyroid Hashimoto's thyroiditis

Background Vitamin D is shown to be a potent immunomodulator. Considering the potential role of low serum vitamin D levels in autoimmune disorder, we evaluated the association between Hashimoto's thyroiditis (HT) (with subclinical or overt hypothyroidism) and serum 25-hydroxyvitamin D (25OHD) levels in an Iranian population. Methods A total number of 86 individuals were enrolled. The case group included 41 patients with hypothyroid HT (overt or subclinical). The control group comprised 45 healthy euthyroid persons. Serum 25OHD levels were measured in all subjects. Results The case: control ratio of geometric means of 25OHD levels was 0.66 (95 % CI: 0.49-0.90; P = 0.008). There was a significant inverse association between serum 25OHD levels and HT (OR: 0.81 for 5 ng/ml increase in 25OHD level, 95 % CI: 0.68-0.96; P = 0.018). This association remained significant after adjustment for potential confounding factors including age, sex and BMI. Conclusions Our study suggested that higher serum 25OHD levels was associated with decreased risk of HT so that each 5 ng/ml increase in the serum 25OHD levels results in 19 % decrease in odds of HT.