Iodine-Induced Fetal Hypothyroidism: Diagnosis and Treatment with Intra-Amniotic Levothyroxine

Background: Iodine is necessary for fetal thyroid development. Excess maternal intake of iodine can cause fetal hypothyroidism due to the inability to escape from the Wolff-Chaikoff effect in utero. Case Report: We report a case of fetal hypothyroid goiter secondary to inadvertent excess maternal iodine ingestion from infertility supplements. The fetus was successfully treated with intra-amniotic levothyroxine injections. Serial fetal blood sampling confirmed fetal escape from the Wolff-Chaikoff effect in the mid third trimester. Early hearing test and neurodevelopmental milestones were normal. Conclusion: Intra-amniotic treatment of fetal hypothyroidism may decrease the rate of impaired neurodevelopment and sensorineural hearing loss.

Fetal Hypothyroidism

ABSTRACT This case report illustrates the prenatal diagnosis of fetal hypothyroidism in a nulliparous 31-year-old woman with a history of four previous cesarean sections. She was presented with chronic renal failure of unknown etiology and had been on dialysis for 3 years along with a subclinical hypothyroidism. At 21.4 weeks of gestation, color Doppler revealed a fetus with symmetrical solid mass in the anterior cervical region with little vascularization compatible with fetal goiter. Aminotic fluid was also increased for gestational age. At 25 weeks of gestation, due to maternal respiratory distress, an amniodrainage was performed. From the same sample, thyroid-stimulating hormone (TSH) was determined yielding 1.3 mIU/mL and 0.1 ng/dL for free T4. At 27 weeks of gestation, membrane rupture occurred. Chorioamniotis was suspected and cesarean section was performed extracting a live 1060 gm female newborn. The newborn was 29 weeks of age by Capurro test and Apgar score was 7/08. On physical examination, a 2 to 3 cm symmetrical tumor was found in cervical region. Admitted to neonatal intensive care unit for mechanical respiratory support, four ampoules of T4 were given, achieving complete regression of thyroid gland size at 15 days of life. At 34 days of age, nosocomial infection, Klepsiella neumonie, was confirmed and death occurred at 40 days of life. Isolated fetal hypothyroidism is rare. Ultrasound evaluation allows the identification of compensatory growth of the thyroid, showing a hypoechoic solid image. In extreme cases, it may cause esophageal obstruction and polyhydramnios as well as cervical hyperextension and dystocia during labor. How to cite this article Ruoti Cosp M, Gruhn E, Ontano M, Calabrese E, Mendoza L. Fetal Hypothyroidism. Donald School J Ultrasound Obstet Gynecol 2016;10(3):326-329.