Hyperthyroidism in pregnancy.

PURPOSE OF REVIEW

Successful outcome in pregnancy hyperthyroidism depends on the cause, interpretation of laboratory tests, and careful use of antithyroid drug (ATD) therapy. Planning of a pregnancy in a woman with active or past history of Graves' hyperthyroidism is mandatory in order to avoid complications.

RECENT FINDINGS

Fetal health may be affected by three factors: poor control of maternal hyperthyroidism, titer of maternal TRAb, and inappropriate use of ATD. Careful assessment of thyroid function through pregnancy and evaluation of fetal development by ultrasonography is the cornerstone for a successful outcome. In a subgroup of women previously treated with ablation therapy, those whose serum TSRAb titers remained elevated, are at risk of having a fetus/neonate with Graves' hyperthyroidism. Use of ATD during lactation is well tolerated, if recommended guidelines are followed.

SUMMARY

Women during their childbearing age with active Graves' hyperthyroidism should plan their pregnancy. Causes of hyperthyroidism in pregnancy include Graves' disease or autonomous adenoma, and transient gestational thyrotoxicosis as a consequence of excessive production of human chroionic gonadotropin by the placenta. Careful interpretation of thyroid function tests and frequent adjustment of ATD is of utmost importance in the outcome of pregnancy. Graves' hyperthyroidism may relapse early in pregnancy or at the end of the first year postpartum.