Correlation Between Vitamin B12 Deficiency and Autoimmune Thyroid Diseases

Background: Autoimmune thyroid diseases (AITD) are the most prevalent organ-specific autoimmune disorders. Vitamin B12 plays an important role in the proper functioning of the immune system. The aim of this study was therefore to investigate the correlation between vitamin B12 deficiency and AITD. Materials and Methods: A total of 306 patients (aged 18-65 years, mean – 37.6 ± 11.3 years and comprising 87 males and 219 females) were studied retrospectively (observational study). Patients were divided into groups: with and without vitamin B12 deficiency, and with and without AITD. Differences between groups were evaluated by Fisher’s exact test for qualitative variables and by Student’s t-test for quantitative variables. Correlations for quantitative factors were determined by the Pearson correlation coefficient and for qualitative factors by Spearman correlation analysis. The sensitivity and specificity of vitamin B12 deficiency for AITD were calculated by ROC analysis. Results: The vitamin B12 level was significantly lower in patients with AITD (and 200.70 + 108.84) compared to controls (393.41+150.78 p<0.0001). Patients with vitamin B12 deficiency were characterized by significantly higher mean values of anti-TPO (236.60+455.74) compared to controls (39.51+165.57 p<0.0001). Vitamin B12 levels were inversely correlated to anti-TPO levels (r=– 0.233, p<0.001). Roc analysis of vitamin B12 as a diagnostic test for AITD gave the area under curve as 0.881 (95% CI: 0.839-0.924), a sensitivity of – 0.947, a specificity of – 0.768, and a cutoff value of – 178.9. Conclusion: The vitamin B12 level correlates significantly to AITD. The concentration of vitamin B12 should therefore be determined in patients with autoimmune thyroiditis as a diagnostic test with high sensitivity and good specificity.