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.