[Clinical implications of occurrence of antithyroid antibodies in pregnant women and in the postpartum period]

Abstract

Antithyroid antibodies are classified to immunoglobulin G. It is a varied group of antibodies as there are antibodies against TSH-receptor, against thyroid peroxidase and also against thyroglobulin. Pregnancy is a period in which the titres of antibodies decrease to protect fetus from abortion; but just after delivery they increase again. The clinical implications of this fact are varied and concern not only the thyroid gland but also other organs. Postpartum thyroid dysfunction (PPD) is one,possible disturbance due to presence of antithyroid antibodies. It can be divided into two various types: a) postpartum thyroiditis, b) Graves'-Basedow disease after delivery. Postpartum thyroiditis (PPT) is an example of autoimmune disease connected with many different factors such as genetic or environmental, but the most important factor is the presence of antibodies against thyroid peroxidase. PPT occurs in 50% of women with high titre of these antibodies. Higher risk of PPT also occurs within women with type I diabetes mellitus in comparison with the population, as well as within women-smokers. It is also proved that women with high titres of antibodies against TSH-receptor are more likely to suffer from Graves'-Basedow disease after delivery. The pathogenesis of postpartum depression is multifactorial. The occurrence of stressful life events (marital disharmony, housing and socioeconomic problems) and some biological factors (e.g. previous psychiatric illnesses) are strongly associated with postpartum depression. Some authors also said that postpartum depression depends on the presence of antithyroid antibodies during pregnancy. It is believed that cytokines which are released during the autoimmune process can affect the central nervous system and can determine changes in behavior. Some authors suggest that changes in concentration of thyroid hormones during the natural history of PPT can be connected with depression after delivery. It is also reported that high titres of antithyroid antibodies are linked with pregnancy loss but the results are not uniform.