Plasma and erythrocyte zinc, copper and selenium in cystic fibrosis.

Plasma and erythrocyte zinc, copper and selenium were measured in 20 cystic fibrosis children, aged 7 to 19 years. Mean plasma zinc and copper levels were not different from those in age-matched controls but very low zinc levels occurred sporadically. Plasma zinc concentrations were significantly lower in patients with moderate-to-severe growth retardation and with severe pulmonary disease as compared to patients without growth failure and with moderate pulmonary disease. Mean erythrocyte zinc (40.8 micrograms/g Hb +/- 9.2) and copper levels (3.56 micrograms/g Hb +/- 0.50) were very significantly increased (30.4 micrograms/g Hb +/- 5.2 and 2.73 micrograms/g Hb +/- 0.30 respectively, for age-matched controls). Mean plasma and erythrocyte selenium levels (63 ng/ml +/- 15 and 329 ng/g Hb +/- 86) were significantly lower than those in age-matched controls (82 ng/ml +/- 13 and 404 ng/g Hb +/- 116). The trace element concentrations in erythrocytes are discussed in relation to the activities of the copper- and zinc-containing enzyme superoxide dismutase and the seleno-enzyme glutathione peroxidase. We consider that more data on trace element metabolism in CF should be collected before specific supplementation is considered.