A child with pericardial effusion and cardiac tamponade due to previously unrecognized hypothyroidism.

We present a 12-year-old Hispanic girl without overt symptoms of hypothyroidism who presented with early cardiac tamponade from pericardial effusion due to previously unrecognized hypothyroidism. Pediatric patients with unexplained pericardial effusions should be screened for hypothyroidism and should be followed closely for the development of tamponade if found to have hypothyroidism.