[Heart failure as early manifestation of neonatal hyperthyroidism. Case report]

Neonatal hyperthyroidism is usually a self-limited condition frequently associated with transplacental passage of thyroid stimulating antibodies secondary to maternal autoimmune disorders. To timely detect mothers with this medical antecedents decreases the risk for fetal adverse events.

To report a case of neonatal hyperthyroidism associated with intrauterine growth restriction and heart failure.

A 36 week-old newborn with birth weight of 1,240 g. Symptoms were tachycardia, distal coldness, exophthalmos, hepatomegaly and tremors. Echocardiogram ruled out structural heart disorders. Due to maternal symptoms suggestive of hyperthyroidism, TSH tests were performed showing 0.01 ulU/ml, free T4 7.7 ng/dl, so the diagnosis of neonatal hyperthyroidism was confirmed. It was treated with methimazole and propanol, alleviating the symptoms and decreasing the levels of free T4.

To know the maternal history helps identify and manage neonatal complications of hyperthyroidism. Heart failure and other cardiopulmonary disorders are determinants of mortality during early neonatal period. High-risk newborns should receive follow up assessments.