Abstract
A 23-year-old man was admitted for acute pericarditis that evolved to cardiac tamponade and shock with need of emergent pericardiocentesis and inotropic support. Corticosteroid therapy was successful, but despite a gradual tapering, the patient relapsed. Incidentally, the patient developed hyperkalemia with hyponatremia. Subsequent hormonal measurements confirmed autoimmune polyglandular syndrome type-2. (Level of Difficulty: Intermediate.).