Graves’ Disease And Pregnancy

Hyperthyroidism in pregnancy

Hyperthyroidism is second to diabetes mellitus as the most common endocrinopathy in pregnancy. Inappropriate secretion of hCG is the most common cause of hyperthyroidism in the first part of gestation. In addition to hydatidiform mole and hyperemesis gravidarum, nonpathologic-conditions including multiple gestation, mild nausea and vomiting, and even normal pregnancies may present with transient undetectable or suppressed serum TSH values. The syndrome of transient hyperthyroidism of hyperemesis gravidarum is defined as severe nausea and vomiting, dehydration, ketonuria, and weight loss of more than 5% by 6 to 9 weeks of pregnancy. Thyroid tests are in the hyperthyroid range, and the abnormalities are related to the severity of symptoms. Tests normalize with resolution of the vomiting, and ATD therapy is not indicated. The natural history of Graves' disease in pregnancy is characterized by aggravation in the first trimester, amelioration in the second half, and recurrence in the year following delivery. ATD treatment is the therapy of choice in pregnancy. Either PTU or MMI may be used; the goal is to keep the FT4I in the upper limits of normal with the minimum dose of ATD. In approximately 30% of patients, ATDs may be discontinued in the last few weeks of gestation. Maternal, fetal, and neonatal complications are frequent when hyperthyroidism is not under control. Postpartum hyperthyroidism may be caused by an episode of silent thyroiditis or Graves' disease.

Hyperthyroidism in pregnancy

The prevalence of hyperthyroidism in pregnancy is about 0.2%. The most common cause is Graves' disease. Maternal, fetal, and neonatal morbidity and mortality may be reduced to a minimum with careful attention to the clinical symptoms and interpretation of thyroid tests. Ideally, hyperthyroid women should be rendered euthyroid before considering conception. The incidence of maternal and neonatal morbidity is significantly higher in those patients whose hyperthyroidism is not medically controlled. Even the incidence of thyroid storm is high in women who are under poor medical supervision in the presence of a medical or obstetric complication. Maternal morbidity includes a higher incidence of toxemia, premature delivery, placenta abruptio, congestive heart failure, and thyroid crisis. In some series, anemia and infections were also reported. Neonatal morbidity includes SGA neonates, intrauterine growth retardation, LBW infants, and prematurity. Fetal goiter and transient neonatal hypothyroidism is occasionally reported in infants of mothers who have been overtreated with ATD. Propylthiouracil and MMI are equally effective in controlling the disease. In most patients, symptoms improved and thyroid tests returned to normal in 3-8 weeks after initiation of therapy. Resistance to ATD is extremely rare, most cases are caused by patient poor compliance. Surgery for the treatment of hyperthyroidism is reserved for the unusual patient who is allergic to both ATD; to those who have large goiters; to those who require large doses of ATD; or to those patients who poorly comply. Fetal and neonatal hyperthyroidism can be predicted in the majority of cases by the previous maternal medical and obstetric history and by the proper interpretation of thyroid tests. Finally, hyperthyroidism may recur in the postpartum period.