Hypothyroidism presenting as cardiac tamponade in Down syndrome.

: Down syndrome is the commonest chromosomal anomaly. It is often associated with hypothyroidism, which may rarely present with cardiac tamponade as the earliest manifestation and prompt treatment with L-thyroxine is life saving. A six-month-old female child diagnosed as a case of Down syndrome presented with shortness of breathing for last 1 1/2 months. Facial dysmorphism, characteristic of Down syndrome was present. Echocardiography revealed large pericardial effusion and right ventricular diagnostic collapse. A case of Down syndrome with hypothyroidism and cardiac tamponade was kept in mind. She was treated with L-thyroxine and clinical status improved.