Selenium deficiency associated with cardiomyopathy: a complication of the ketogenic diet

The ketogenic diet (KD) is an efficacious treatment for intractable epilepsy, associated with infrequent side effects. The KD is known to be deficient in most vitamins and minerals and may be deficient in trace minerals. We report biochemical selenium deficiency in nine patients on the KD, including one who developed cardiomyopathy.

A whole-blood selenium level was obtained on the symptomatic patient after noting the patient's poor appearance on physical examination. Children already treated and children beginning the KD were then evaluated prospectively for selenium status by measuring whole-blood or serum selenium as part of routine laboratory evaluation every 3 months.

The index case had no detectable whole-blood selenium. Cardiac physical examination and ECG were normal, but the echocardiogram revealed cardiomyopathy. Thirty-nine additional children had the selenium status evaluated. Eight had selenium levels below the normal range (six initially, and two developed low selenium levels on serial testing). They were referred for cardiology evaluations, which were normal. Selenium supplementation improved levels in all children. Low levels were seen in some children after only a few months of treatment.

The nutrient adequacy of the currently used KD has not been fully evaluated. The nutrient content of KD with usual supplements may not meet Recommended Dietary Allowances (RDA) for selenium and may not provide other trace minerals in adequate amounts. At our center, selenium deficiency was found in 20% of the patients evaluated. Screening for selenium deficiency is suggested if the patient KD regimen does not meet > or =75% of the RDA or if the child is symptomatic. Nutrient supplementation should provide adequate trace elements for children treated with the KD. The KD requires close monitoring of the overall nutritional status.