Resting Energy Expenditure in Children with Sickle Cell Disease

Abstract Children with sickle cell disease (SCD) have decreased height and weight when compared to their healthy peers, but exact reasons for poor growth have not been established. Researchers have reported that children with SCD have resting energy expenditure (REE) that is 18% above healthy controls and 13% above energy prediction equations. Although there are no energy prediction equations specific to patients with SCD, the Harris-Benedict (HB) equations are commonly used to predict the energy needs of a wide range of people, and the validity of these equations has been established in healthy children. In order to examine the energy needs of children with SCD, we compared the HB equations to measured energy expenditure in 21 children with SCD. Their ages ranged from 5–17 years (mean 11.5 ± 3.5, median 13); 12 were female. We measured REE by indirect calorimetry using a CPX-MAX-D Cardiopulmonary Gas Exchange System (Medical Graphics), in a supine position, after an overnight fast The patients had a mean ideal body weight of 94.7 ± 7.3%. Their mean fat free body mass (bioelectrical impedance, RJL Systems) of 85.6 ± 7.8%, compared to an estimated 80% in normal children of the same age. Four patients were below the 5 th percentile for height and 6 for weight, and 7 patients had triceps skinfold thickness (Lange calipers) ⩽ 5 th percentile for age. The measured REE (1384 ±342) was significantly higher than the predicted (1221 ± 265). The ratio of measured REE to predicted REE was 1.14 (p=0.001). We conclude that energy prediction equations underestimate the REE of patients with SCD by 14%. Although patients in this study were smaller and leaner than the general population, their energy needs were higher than predicted. Their elevated REE may be due to the higher percentage of lean body mass and/or manifestations of SCD, such as chronic anemia. This increased energy requirement, in the absence of adequate energy intake may contribute to the poor growth of children with SCD.