Selenium deficiency-induced cardiomyopathy: a case report.

Background: Selenium is an essential trace element involved in redox homeostasis, thyroid function, and immune regulation. Deficiency is uncommon in developed countries but occurs in patients with malabsorption, long-term parenteral nutrition, or chronic kidney disease on dialysis. Selenium deficiency is a rare but treatable cause of non-ischaemic cardiomyopathy and arrhythmias, which can be fatal if untreated. Due to its rarity, it is often unrecognized, its pathophysiology remains unclear, and the threshold for irreversible myocardial damage is not well defined. Case summary: We present the case of a 63-year-old man with Crohn's disease and progressive renal failure admitted for haemodialysis initiation. Over 3 months, a rapid decline in cardiac function was observed, and an electron microscopic study of the myocardial biopsy specimen revealed marked myocardial cell degeneration. Subsequent detailed physical examination suggested leukonychia, and laboratory tests confirmed low serum selenium levels. Following selenium supplementation, his cardiac function and symptoms of heart failure improved. Discussion: This case highlights the importance of considering selenium deficiency in the differential diagnosis of non-ischaemic cardiomyopathy, particularly in patients with risk factors such as intestinal malabsorption and dialysis. Early recognition and targeted supplementation can result in complete recovery of cardiac function, even in cases with histological evidence of structural myocardial degeneration.