ENERGY-EXPENDITURE AND GENOTYPE OF CHILDREN WITH CYSTIC-FIBROSIS

Increased energy expenditure, poor dietary intake, and fat malabsorpti on in patients with cystic fibrosis (CF) frequently lead to growth fai lure and malnutrition, which are associated with pulmonary failure and decreased survival. The study purpose was to understand better the en ergy expenditure and requirements in the mild pulmonary disease state in children. Resting and total energy expenditure were measured in 6- to 9-yr-old, pancreatic-insufficient children with CF (n = 25) and con trol children (n = 25) of similar age, gender, and weight. The effect of the most common genotype, homozygous Delta F508, on energy expendit ure was also investigated. Dietary intake, degree of fat malabsorption , body composition, physical activity, and clinical status were determ ined. The CF group had a 9% increase in resting energy expenditure, wh ich was not related to genotype or severity of lung disease. Both CF g enotype subgroups (Delta F508 homozygous and all others) had a similar , modest resting energy expenditure increase. Total energy expenditure was increased by 12% in the entire CF group and by 23% in the Delta F 508 homozygous CF subgroup compared with controls. The total energy ex penditure increase in Delta F508 homozygous children may be related to increased voluntary physical activity, reflecting no activity reducti on associated with lung disease, or to aa unidentified genotype-relate d mechanism. The clinical implication is that a detailed physical acti vity assessment should be evaluated along with resting energy expendit ure, either measured or estimated by equations, when daily energy need s are being determined for children with CF.