Fetal Hyperthyroidism Secondary to Maternal Basedow-Graves' Disease.

Area of Science:

• Endocrinology
• Maternal-Fetal Medicine
• Neonatology

Background:

• Fetal hyperthyroidism is a rare, potentially life-threatening prenatal condition.
• Diagnosis involves maternal history of Basedow-Graves' disease and elevated thyrotropin receptor antibodies (TRAbs).
• Treatment typically involves antithyroid drugs.

Observation:

• A 29-year-old mother with a history of Basedow-Graves' disease presented with elevated TRAbs during an unplanned pregnancy.
• Fetal ultrasound at 22 weeks gestation revealed tachycardia, goiter, exophthalmos, and suspected craniosynostosis.
• Maternal thyroid-stimulating hormone (TSH) levels were suppressed concurrently with fetal treatment initiation.

Findings:

• Fetal hyperthyroidism was diagnosed and treated with methimazole in utero.
• The infant was born preterm with confirmed hyperthyroidism and subsequently treated with methimazole.
• Maternal thyroid function normalized postpartum, with the cause of suppressed TSH during pregnancy remaining unclear.

Implications:

• This case highlights the importance of monitoring TRAbs in pregnant women with a history of Basedow-Graves' disease.
• In utero treatment of fetal hyperthyroidism can lead to favorable neonatal outcomes.
• Further research is needed to elucidate the mechanisms behind maternal TSH suppression during pregnancy in such cases.