The association between vitamin D and Hashimoto’s thyroiditis

Hashimoto’s thyroiditis is probably the most common autoimmune disease treated in endocrinology clinics. It is still contraversial whether vitamin D deficiency is a cause or result of Hashimoto’s throiditis. However pleiotropic effects of vitamin D have been described recently in many studies that its deficiency could be a predisposing factor for autoimmune diseases. This clinical research aims to show the relationship between vitamin D deficiency and Hashimoto thyroiditis. One hundred twenty six participants who admitted to family medicine clinics in year 2017 during a 6 months period of time at Izmir Katip Celebi University Hospital in Turkey were included in our cross sectional study. Openepi sample size calculator predicted 95% of confidence interval, 80% of power and 5% of tolerence with consisting a number of 38 individuals in each group. Patients were grouped as previously diagnosed Hashimoto’s thyroiditis, newly diagnosed Hashimoto’s thyroiditis and healthy individuals. After supplying reserved participants which consist of 10% of the total, 42 individuals recruited in each group. Vitamin D levels were significantly lower in both previously diagnosed Hashimoto and newly diagnosed Hashimoto groups than control group with values of 12.62ng/dl, 11.76ng/dl and 15.03ng/dl respectively (p <0.05). Vitamin D insufficiency found to be correlated with TSH, fT4, anti-TPO, anti-Tg, kreatin, PTH levels, BMI, smoking and female gender (p <0.05). Multiple regression analysis of these parameters via retrospective elimination method showed that vitamin D is negatively correlated with BMI and anti-Tg. On the other a positive correlation with fT4 was also shown in the study. Vitamin D deficiency may be a predisposing factor for Hashimoto’s disease.