Gestational Transient Thyrotoxicosis Complicated by Thyroid Storm in a Patient With Hyperemesis Gravidarum.

We describe a patient with gestational transient thyrotoxicosis (GTT) associated with hyperemesis gravidarum (HG) in a twin gestation complicated by thyroid storm resulting in intrauterine fetal demise. GTT is a well-documented complication of the first trimester of pregnancy that may affect up to 60% of pregnancies with HG. Typically, GTT is not associated with unfavorable maternal or fetal outcomes and has a spontaneous resolution. Aside from supportive care, the use of antithyroid drugs (ATD) in GTT is not regularly recommended. Although to our knowledge one similar case has been reported in the literature, the incidence of thyroid storm in GTT has not yet been established. Our case highlights that, although rare, GTT may be complicated by thyroid storm resulting in adverse maternal and fetal outcomes. Our case further suggests that consideration of ATD use in GTT should be given in pregnancies with higher serum human chorionic gonadotropin (hCG) concentration as occurs in HG and multiple pregnancies.