TPO and vitamin D deficiency: Mazokopakis et al. found that anti-TPO levels were significantly higher in vitamin D-deficient patients with Hashimoto’s thyroiditis (HT) (n = 186) compared to HT patients with no vitamin D deficiency (n = 32) (364 ± 181 vs. 115.8 ± 37.1 IU/mL, p < 0.0001) [36], whereas Bozkurt et al. found that serum 25(OH)D levels were inversely correlated with anti-TPO (p < 0.001) and anti-TG levels (p < 0.001) in subjects with HT [36].