PROSPECTIVE EVALUATION OF RESTING ENERGY-EXPENDITURE, NUTRITIONAL-STATUS, PULMONARY-FUNCTION, AND GENOTYPE IN CHILDREN WITH CYSTIC-FIBROSIS

Growth failure and malnutrition are common clinical features in cystic fibrosis (CF), but the relationships among resting energy expenditure (REE), pulmonary function, and nutritional status, are poorly underst ood. To better understand these relationships, REE, growth, nutritiona l status, and pulmonary function were measured prospectively in 25 pre pubertal children with CF and 26 prepubertal control subjects of simil ar age and gender over a 3-y period. All subjects with CF had pancreat ic insufficiency and mild pulmonary disease. REE was elevated for the CF children compared with control subjects throughout the study. This increased REE was not associated with declining pulmonary function. Lo ngitudinal analyses revealed different patterns of change over time in boys and girls, such that REE significantly increased in the girls wi th CF and pulmonary function decreased in the boys. Boys with CF exper ienced a decline in weight Z score and percent ideal body weight, wher eas the girls with CF experienced a decline in height Z score, Pulmona ry function was not associated with REE, but nutritional status (perce nt ideal body weight) and genotype (Delta F508 homozygotes versus othe rs) were predictive of changes in pulmonary Function over time. Fat fr ee mass and height were found to be the best predictors of REE, and af ter accounting for these important body size and composition variables , differences in REE between buys and girls and CF and control groups increased over time. These findings identify the importance of investi gating gender differences in the course of disease and considering REE as an early indicator of disease severity independent of pulmonary fu nction.