Low blood selenium levels in patients with cystic fibrosis compared to controls and healthy adults

Frank clinical selenium deficiency has been described in cystic fibrosis (CF), and a relative deficiency has been proposed as contributing to the pathogenesis of the disease. Because of these possibilities, we investigated the relationship between overall nutritional status in CF with measures of selenium nutriture. Fifteen stable outpatients with CF (group I) were compared to 13 age-matched controls (group II) and 27 healthy adults (group III). Whole blood, plasma, and red blood cell selenium levels were reduced by 31%, 29%, and 33%, respectively, in CF patients vs controls (all p less than 0.001). In addition, both groups I and II showed significantly lower blood selenium levels than healthy adults (p less than 0.005). Nutritional assessment revealed CF patients to be undernourished, with significant decreases in serum albumin (p less than 0.025), weight-for-height deficit (p less than 0.01), and weight-for-age (p less than 0.025) vs controls. However, only the triceps skinfold (TSF) measurement correlated significantly with selenium status (r = 0.56: p less than 0.05 for whole blood selenium vs TSF). We conclude, based on the magnitude of decrement in blood selenium, that it is unlikely that selenium plays a significant primary pathogenic role in cystic fibrosis. However, these patients are at high risk for developing clinical selenium deficiencies. The measurement of blood selenium levels using appropriate age-matched normal standards should be mandatory in all CF patients with malnutrition, or in those requiring parenteral nutritional support.