Fetal goitrous hypothyroidism followed by neonatal transient hyperthyroidism. A case report.

We report a case of fetal goitrous hypothyroidism followed by neonatal transient hyperthyroidism. A fetal goiter (26 x 38 mm) was detected by ultrasound and magnetic resonance imaging at 29 weeks of gestation. Hypothyroidism was confirmed by cordocentesis, which revealed an elevated TSH (255 microIU/ml) and a low free T4 (0.4 ng/dl). The fetal goiter decreased in size after treatment with four 240-microgram intra-amniotic administrations of levothyroxine. A 2,829-gram male neonate was delivered vaginally at 37 weeks of gestation, showing an euthyroid status at birth. On day 3, free T3 was 6.9 pg/ml and free T4 was 6.4 ng/dl, indicating hyperthyroidism. This persisted for 4 months. His thyroid functions reverted to normal at 4 months of age and have been within normal range since. Undetermined factors might be involved in the development of thyroid dysfunction in the perinatal period. Copyright 2003 S. Karger AG, Basel