Influence of endogenous T3-autoantibodies on thyroid hormone measurements in a woman with transient postpartum thyroiditis

Autoimmune Abnormalities of Postpartum Thyroid Diseases

The year following parturition is a critical time for the de novo appearance or exacerbation of autoimmune diseases, including autoimmune thyroid disease. The vast majority of postpartum thyroid disease consists of postpartum thyroiditis (PPT) and the minority by Graves' disease and non-autoimmune thyroiditis. PPT has a worldwide prevalence ranging from 1 to 22% and averaging 5% based on a review published in 2012. Several factors confer risk for the development of PPT. Typically, the clinical course of PPT is characterized by three phases: thyrotoxic, hypothyroid, and euthyroid phase. Approximately half of PPT women will have permanent hypothyroidism. The best humoral marker for predictivity, already during the first trimester of gestation, is considered positivity for thyroperoxidase autoantibodies (TPOAb), though only one-third to half of such TPOAb-positive pregnant women will develop PPT. Nutraceuticals (such as selenium) or omega-3-fatty acid supplements seem to have a role in prevention of PPT. In a recent study on pregnant women with stable dietary habits, we found that the fish consumers had lower rates of positivity (and lower serum levels) of both TPOAb and thyroglobulin Ab compared to meat eaters. Finally, we remind the reader of other diseases that can be observed in the postpartum period, either autoimmune or non-autoimmune, thyroid or non-thyroid.

Thyroid hormone autoantibodies (THAA) in three sisters: a four-year follow up

We have found three sisters who had thyroid hormone autoantibodies (THAA) in serum. Two of them were hypothyroid due to Hashimoto's thyroiditis. They were treated with synthetic thyroxine (T4) (Case 1) or T4 and triiodothyronine (T3) (Case 2). The other sister (Case 3) was euthyroid throughout the investigation period. Changes in the titers of THAA, antithyroglobulin (Tg) antibodies as well as in the concentrations of thyrotropin (TSH), and total and free thyroid hormones (T3, T4, FT3, and FT4) in sera from each patient were examined for four years. A significant positive correlation was observed between titers of THAA and anti-Tg antibodies in both Case 1 (anti-T3 and anti-T4) and 2 (anti-T4). On the other hand, a significant negative correlation between titers of anti-T3 and anti-Tg antibodies was observed in Case 3. These results suggest that antigen of THAA might be Tg in Case 1 and 2 and mechanism(s) of the production of THAA of Case 1 might be different from that of Case 1 and 2 in terms of their antigen or immune recognition of Tg.