Endocrine Abstracts

Introduction

Recently, apart from its main physiologic role, the active form of vitamin D has also been recognised to have anti-inflammatory and immune-modulating properties. Accumulating evidence suggests that Vitamin D deficiency is associated with increased prevalence of various autoimmune diseases, and in particular, with autoimmune thyroid disease. Despite contradicting evidence, the balance is tipping towards inverse correlation between vitamin D deficiency and autoimmune thyroid diseases. To the best of our knowledge, this association has not been studied before in South Caucasia, a large geographical area spanning across four countries, including Georgia. Therefore, this study aimed to investigate whether vitamin D deficiency was associated with increased prevalence of autoimmune thyroiditis among Georgian adults.

Methods

Study population consisted of patients aged >18 years with measurements of both serum vitamin D (25OHD) and thyroid peroxidase antibody (TPOAb) levels in two medical centres in Georgia from July 2016 to August 2020. The participants were divided into cases (vitamin D deficient) and controls (vitamin D sufficient/insufficient). 25OHD and TPOAb baseline levels were compared using Kruskal–Wallis rank-sum test. The strength of association was quantified by odds ratio. The strength and direction of association between vitamin D and TPOAb were measured with Spearman’s rank-order correlation. Statistical significance was accepted at 95% confidence interval (P<0.05).

Results

170 patients had measurements of both 25OHD and TPOAb, and were included in the analysis, with a mean age of 43.9 ± 15.49 years (male to female ratio of 1:4.28). 59.4% (n = 101/170) had vitamin D deficiency and 53.5% had positive TPOAb (n = 91/170). In the case group, 60.4% (n = 61/101) had positive TPOAb, compared to 43.5% (n = 30/69) in controls. TPOAb baseline levels were higher in cases (mean: 191.0, S.D.: 53.9), compared to the controls (mean: 102.7, S.D.: 155.4) (P = 0.0328). TPOAb was significantly higher in the case group (P = 0.0439) with an odds ratio of 2.0 (OR>1, 95% CI: 1.1–3.7, P = 0.0308). When adjusted for age, gender, and BMI, a percentage change of 14.8% was observed, increasing the odds ratio to 2.3 (OR>1, 95% CI: 1.2–4.5, P = 0.0169). A significant inverse correlation was observed between vitamin D and TPOAb levels (rho = -0.16, P = 0.0367).

Conclusion

Our findings suggest a significant and inverse correlation between vitamin D deficiency and thyroid autoimmunity among Georgian adults. Further prospective studies are warranted to ascertain a causal relationship between vitamin D deficiency and autoimmune thyroiditis in our population.