Prenatal presentation of a hyperfunctioning thyroid nodule

Objectives: Fetal and neonatal hyperthyroidism are most commonly seen in patients whose mothers have Graves' disease. Rarely, it can be caused by non-autoimmune conditions. As these conditions are rare, the workup and treatment is not uniform and can lead to persistent symptoms and long-term negative health effects. Case presentation: This report describes a patient with congenital hyperthyroidism from a toxic adenoma presenting with fetal tachycardia. The patient was initially managed medically after birth, but was eventually treated with thyroidectomy. Conclusions: This case report highlights an additional, important, differential diagnosis for fetal hyperthyroidism when maternal Graves' disease has been ruled out.