Summary

We present a case of pericardial tamponade caused by hypothyroidism. A 66-year-old man presented with acute chest pain radiating to the back. Computed tomography ruled out an aortic dissection but revealed a large pericardial effusion, which was confirmed on transthoracic echocardiography showing features of tamponade. The effusion was drained and subsequent thyroid function tests showed profound hypothyroidism. No other cause of the pericardial effusion could be identified. Despite the prompt initiation of levothyroxine (T4) replacement therapy, the effusion re-accumulated over a period of 10 days and required further drainage. Following that, aggressive thyroxine replacement therapy using liothyronine (T3) was initiated and there was no further re-accumulation. Hypothyroidism should be suspected in any cases of pericardial effusion where the cause is not obvious. We should be vigilant of re-accumulation, and T3 replacement therapy should be considered in that situation.