Pericardial effusion in severe hypothyroidism in children.

Pleural and pericardial effusion is a rare complication of severe hypothyroidism in children but can be present in 10 to 30% of adults. Most pediatric cases have been in children with Down syndrome. In this report, six cases of pericardial effusion in children with severe hypothyroidism with and without trisomy 21 are presented. In all patients, the pericardial effusion was managed successfully without pericardiocentesis. The effusions resolved completely in 2 to 12 months after initiation of thyroxin replacement. In conclusion, hypothyroidism should be considered in any child with unexplained pericardial or pleural effusions. Early recognition and treatment with thyroid hormone replacement could eliminate the need for unnecessary diagnostic procedures and invasive treatment measures and reduce the risk of progression to cardiac tamponade.