Evaluation of vitamin D and vitamin B12 levels in patients with and without Hashimoto’s thyroiditis: A case-control study

Hashimoto's thyroiditis (HT) is a common autoimmune thyroid disorder whose pathogenesis may be influenced by various biochemical and immunological parameters. Recent evidence suggests that vitamin D and B12 levels may play a role in autoimmune diseases. This study aimed to evaluate vitamin D and B12 levels in patients with HT and to examine their associations with disease pathogenesis and clinical features. This retrospective case-control study included patients who visited a family medicine outpatient clinic. The case group consisted of patients diagnosed with HT confirmed by positive anti-thyroid peroxidase antibody (anti-TPO) and/or anti-thyroglobulin antibody (anti-Tg). The control group included individuals without chronic diseases and with negative thyroid autoantibodies. Data on age, gender, history of hypothyroidism, vitamin D, vitamin B12, anti-TPO, and anti-Tg levels were collected and analyzed. Binary logistic regression was used to identify predictors of HT. A statistically significant correlation was found between vitamin D levels and HT, age, history of hypothyroidism, anti-TPO, anti-Tg, and vitamin B12 levels. There was no significant association between vitamin D and gender. Logistic regression analysis revealed that older age, female gender, and lower vitamin D and B12 levels were independently associated with an increased risk of HT. Vitamin D and B12 deficiencies appear to be associated with the presence and progression of HT. These findings highlight the potential role of nutritional and immunological markers in the disease's clinical course. Further prospective studies are warranted to confirm causality and inform clinical management.