Differences in resting energy expenditure between male and female children with cystic fibrosis.

Objectives: To evaluate which factors might contribute to raised resting energy expenditure (REE) in patients with cystic fibrosis (CF).

Study Design: REE and anthropometry were measured in 134 (males = 68) children with CF and 100 (males = 51) controls (range, 3-18.7 years) in an outpatient setting. Bacterial colonization, liver disease, inhaled steroid use, pancreatic and pulmonary function, sex, and genotype were determined and regression analysis was used to determine the predictors of REE in the group with CF.

Results: REE for children with CF was increased on average by 7.2% compared with controls. This increase was greater for females than for males. REE in males was positively associated with fat-free mass (FFM), pancreatic insufficiency (PI), and liver disease, and negatively associated with pulmonary function, whereas in females, REE was positively associated with FFM and PI. REE (adjusted for FFM) was higher in children with a severe mutation (5495 +/- 47 kJ) compared with a mild mutation (5,176 +/- 124 kJ, P <.02).

Conclusions: PI, severe mutations, and female sex are the main contributing factors to elevated REE in patients with CF with near normal pulmonary function.