We present a 39-year-old male patient with Down syndrome who was evaluated for fatigue, palpitations and bouts of cyanosis. Physical examination showed features of trisomy-21(Down syndrome), with a slow pulse rate, distant cardiac sounds and absent apex beat. He had normal jugular venous pressure without pulsus paradoxus. The ECG showed QRS microvoltage and flattened P and T segments. The 48-hour ambulatory ECG depicted normal sinus rhythm with intermittent short PR interval without tachyarrhythmias. The chest Xray revealed cardiomegaly without pulmonary venous congestion. Although serial transthoracic echocardiographic examination demonstrated pericardial effusion with features of tamponade, there were no overt signs of clinical cardiac tamponade. Biochemically, the serum thyroxine of 3 pmol/l (normal 10 to 25) and thyroid-stimulating hormone of 160 mU/l (normal 0.20 to 4.20)) were compatible with hypothyroidism. The patient was treated with L-thyroxine sodium daily, which was gradually increased to 0.125 mg daily. Within a few months he lost weight and became more alert; furthermore, the symptoms of hypothyroidism and the pericardial effusion resolved. It can be concluded that Down syndrome may be associated with hypothyroidism and pericardial effusion. These were alleviated following hormone replacement. Regular evaluation of thyroid function tests is important in Down syndrome. (Neth Heart J 2007;15:67-70.)
