Antepartum diagnosis of goitrous hypothyroidism by fetal ultrasonography and amniotic fluid thyrotropin concentration.

Ultrasonography of a 26-week-old fetus suggested the presence of a goiter. Amniocentesis was performed at 26 and 38 weeks gestation to evaluate thyroid function. An elevated amniotic fluid TSH level was found on both occasions, though amniotic fluid T4, T3, and rT3 levels were similar to those of euthyroid fetuses. The diagnosis of goitrous hypothyroidism was confirmed at birth. Therapy with thyroid hormone was instituted on the first day of life. Growth and development of the infant have been normal during the first year of his life. We suggest that the measurement of amniotic fluid TSH can be useful in the diagnosis of intrauterine primary hypothyroidism.