In a study of 40 adult patients with hypothyroidism due to Hashimoto disease, Papanas et al. found that the serum interleukin (IL)-6 level was significantly and positively correlated with the LT4 dose, the LT4 dose per kg body weight, and the serum tumour necrosis factor alpha level but was significantly and negatively correlated with the serum TT3 level and the serum T3/T4 ratio [104]—suggesting that IL-6 inhibited the deiodination of T3 and rT3. This evidence concerns the gene IL6 and Hashimoto thyroiditis.