INTRODUCTION:

Fetal thyrotoxicosis, often caused by
maternal Grave's disease, can have adverse effects on fetal outcomes, such as
growth impairment or fetal hydrops. Therefore, intrauterine treatment is
recommended.

OBJECTIVE:

To describe the experience of
intrauterine medical treatment of fetal thyrotoxicosis.

CASE:

A 19-year-old woman with a history of
Grave's disease in a euthyroid clinical status after subtotal thyroidectomy
became pregnant 2 months after thyroidectomy. At gestational age 28 weeks,
persistent fetal tachycardia was identified and the diagnosis of fetal
thyrotoxicosis was established by fetal thyroid function test on umbilical cord
blood obtained by cordocentesis. Intrauterine treatment for hyperthyroidism was
initiated with antithyroid drugs (150 mg/day of propylthiouracil) via maternal
oral administration. Fetal heart rate, size of fetal thyroid gland and
umbilical cord blood sampling for thyroid function test were monitored. Fetal
heart rate became normal and fetal thyroid function tested on fetal cord blood
at 1 month after antithyroid fetal therapy was also normal. Fetal
thyrotoxicosis improved but the mother had some degree of hypothyroidism from
fetal therapy and needed thyroid hormone replacement. The remaining course of
gestation was uneventful. The patient had spontaneous labor and delivery at 38
weeks of gestation resulting in normal female baby, 2,900 g, and had no
clinical of neonatal thyrotoxicosis. Maternal thyroid medications were stopped
immediately after birth.

CONCLUSION:

Intrauterine treatment of fetal
thyrotoxicosis with medication via the maternal circulation can possibly
improve fetal outcome.