A Case of a Dialysis Patient with Methylmalonic Acidemia and Impaired Cardiac Function Ameliorated by Selenium Supplementation

Chronic kidney disease, maintenance hemodialysis (HD), and enteral nutrition without selenium can readily result in selenium (Se) deficiency, leading to reversible symptoms such as cardiomyopathy and alopecia. In cases complicated by heart failure, mortality has been documented. When selenium deficiency is suspected, it is imperative to measure serum selenium levels and administer appropriate supplementation. In HD patients, heart failure constitutes a primary cause of mortality, and selenium supplementation may contribute to the prevention of cardiovascular complications and improve patient outcomes.

A 26-year-old male who was diagnosed with methylmalonic acidemia in infancy and has been on enteral nutrition via tube feeding since early childhood. Due to the underlying disease, he developed end-stage renal failure at age 16 and started hemodialysis (HD). At age 24, he experienced hair loss; at age 25, echocardiography showed a decreased left ventricular ejection fraction (LVEF) of 30%. Coronary CT showed no lesions requiring treatment, but a selenium deficiency was found with a serum selenium level of 5.5 μg/dL. After each HD session, intravenous sodium selenite (Acelend®) was started at 50 μg/week and gradually increased up to a final dose of 200 μg/week. Four months after initiating supplementation, the serum selenium increased to 9.6 μg/dL, LVEF improved to 55%, and the hair loss was also suppressed. Since then, serum selenium has been maintained at 8–10 μg/dL with continued administration of 200 μg/week.

This case represents a high-risk example in which the factors of "long-term enteral nutrition with low selenium content" and "maintenance hemodialysis" overlapped, and it met all the diagnostic criteria of the guidelines for selenium deficiency management: (1) symptoms such as hair loss and cardiomyopathy, (2) exclusion of other diseases, (3) serum selenium ≤ 10.0 μg/dL in those aged 19 years or older, and (4) improvement of symptoms upon supplementation. In HD patients, selenium deficiency can be exacerbated by decreased intake due to phosphorus-restricted diets, losses through dialyzers, chronic inflammation and oxidative stress, and abnormal body distribution. In hemodialysis patients with multiple deficiency factors as in this case, measuring serum selenium and performing supplementation and regular monitoring based on the guidelines is highly meaningful. Selenium supplementation has been reported to improve nutritional and inflammation markers as well as cardiac function, and may contribute to improved survival in hemodialysis patients. Conversely, selenium supplementation poses a risk of toxicity; therefore, precise dosage adjustments and rigorous monitoring are imperative to prevent overdose.

In patients undergoing hemodialysis and long-term enteral nutrition who present with unexplained decreases in LVEF or hair loss, clinicians should promptly suspect selenium deficiency and perform serum selenium measurements, along with appropriate supplementation and monitoring. Proper selenium supplementation can potentially lead to reversible improvement of cardiac function.