Increased energy expenditure in cystic fibrosis is associated with specific mutations

Abstract

1. Measurements of resting metabolic rate were made by open-circuit indirect calorimetry in 78 unrelated cystic fibrosis patients and 30 healthy control subjects. The aims of this study were: (i) to determine the range of variability in resting metabolic rate in cystic fibrosis, (ii) to relate this to pulmonary function and body size, and (iii) to investigate the hypothesis that, in cystic fibrosis, genotype exerts a significant influence on energy requirements. 2. There was no significant difference in age or body weight between patients with cystic fibrosis and control subjects. Resting metabolic rates for control subjects fell within +/- 10% of predicted values. Fifty-nine per cent of patients with cystic fibrosis had elevated resting metabolic rates (i.e. greater than 111% of predicted). Genotype analysis divided the patients with cystic fibrosis into three groups: delta F508 homozygotes, delta F508 heterozygotes and others. Patients homozygous for the delta F508 allele had a significantly higher resting metabolic rate (121% of predicted, 95% confidence interval 116-126%), compared with other genotypes (P less than 0.005). 3. There were significant differences in pulmonary function between the groups (P less than 0.005). However, after adjustment of individual resting metabolic rates for differences in pulmonary function by using analysis of covariance, resting metabolic rates remained significantly higher for delta F508 homozygotes than for other genotypes (P less than 0.05). 4. We conclude that there is a significant contribution to resting metabolic rate in cystic fibrosis associated with specific mutations that is not explained by declining pulmonary function.(ABSTRACT TRUNCATED AT 250 WORDS)

Energy cost of physical activity in cystic fibrosis

“…The differences were signi®cant when expressed in absolute terms and also in terms of body weight, FFM and p FFM. There is some evidence that this energy metabolism disorder is genetically conditioned (O'Rawe et al, 1992;Thomson et al, 1996), however the current study did not support this hypothesis. There was no relationship between REE and genotype, which is consistent with others (Fried et al, 1991;Tomezsko et al, 1994).…”

“…It has been con®rmed that REE is elevated in patients which is consistent with previous research (Vaisman et al, 1987a,b;Buchdahl et al, 1988;O'Rawe et al, 1992;Grunow et al, 1993;Horswill et al, 1994;Bell et al, 1995Bell et al, , 1999Stallings et al, 1998). There were also signi®cant increases in the ECA in patients with CF during walking, even when the contribution of REE was accounted for.…”

“…REE in patients with CF is often reported to be 10 ± 20% greater than in healthy subjects (Vaisman et al, 1987a,b;Buchdahl et al, 1988;O'Rawe et al, 1992;Grunow et al, 1993;Horswill et al, 1994;Bell et al, 1995Bell et al, , 1999Stallings et al, 1998). Although the speci®c reasons for this increase are unclear, the rise has been attributed to a number of possible mechanisms.…”

“…Although the speci®c reasons for this increase are unclear, the rise has been attributed to a number of possible mechanisms. These include declining pulmonary mechanics (Vaisman et al, 1987a;Buchdahl et al, 1988;Fried et al, 1991;Amin & Dozor, 1994), malnutrition (Vaisman et al, 1987a,b;Naon et al, 1993;Zemel et al, 1996), in¯ammation of the infectious agents within the lungs (Buchdahl et al, 1988;Naon et al, 1993;Steinkamp et al, 1993;Bell et al, 2000), genetics (O'Rawe et al, 1990(O'Rawe et al, , 1992Thomson et al, 1996;Zemel et al, 1996) and cellular iron transport defects (Feigal & Shapiro, 1979;Stutts et al, 1986). …”

Longitudinal investigation of energy expenditure in infants with cystic fibrosis

“…There are now much data to show that resting energy expenditure (REE) is elevated in CF (Buchdahl et al, 1988;Parsons et al, 1983;Fried et al, 1991;O'Rawe et al, 1992;Spicher et al, 1991;Steinkamp et al, 1993;Grunow et al, 1993;Tomezko et al, 1994;Horswill et al, 1994;Bell et al, 1996;Zemel et al, 1996). Controversy exists, however, with regard to the factors responsible and whether an increased TEE is a consistent observation among individuals with CF.…”