Assessment of Vitamin D Level in Autoimmune Thyroiditis Patients and a Control Group in the Polish Population

Vitamin D, known for its role in calcium-phosphorus homeostasis, is also a significant immunomodulatory factor. Vitamin D deficiency has been reported in some autoimmune disorders. Recently, vitamin D level in autoimmune thyroiditis (HT - Hashimoto's thyroiditis) has become the subject of researchers' interest.This study aims to assess vitamin 25-OH-D3 levels in HT patients in comparison to a control group in the Polish population. This would be the first attempt conducted in this region with such poor sunlight exposure.The group we studied consisted of 62 subjects diagnosed with HT (mean age 49.15±15.51) and 32 healthy controls matched with age and sex (mean age 46.09±14.32). All blood samples were collected in the first quarter of the year to minimize the impact of seasonal fluctuations of vitamin D concentrations.In the HT group the mean vitamin D level was 20.09 nmol/L (SD±12.66), compared to 30.31 nmol/L (SD±19.49) in the controls, p=0.014. None of the patients and the controls was vitamin D sufficient (75-125 nmol/L). The deficiency (<50 nmol/L) was significantly more common among HT patients compared to the controls (61-98.4% vs. 27- 84.4%, p=0.029).In conclusion, we found that serum vitamin D concentration is significantly lower in HT patients in comparison to the control group. This suggests vitamin D deficit as one of the risk factors for HT development. Observed vitamin D level was also low in the control group, therefore wider supplementation in general population should be recommended.