Energy expenditure in obesity associated with craniopharyngioma

Background and purpose Obesity is a common yet incompletely understood complication of childhood craniopharyngioma. We hypothesized that craniopharyngioma is associated with specific defects in energy balance compared to obese control children. Methods Eleven craniopharyngioma patients were recruited for a study on body composition and energy balance. Eight subjects were obese. The obese craniopharyngioma patients had a mean age (±SD) of 11.2±1.7 years. The average bodymass index z score was 2.33 (±0.32). A previously studied group of obese children (BMI z score 2.46±0.46) served as controls. Resting energy expenditure (REE) was determined by indirect calorimetry and body composition by dual energy X-ray absorptiometry in all children. Results Obese craniopharyngioma patient subjects had increased mean (±standard error) fat-free mass compared to obese controls (57%±0.88 % vs 50.0%±0.87%, p=0.02). The obese craniopharyngioma patients had a 17% lower REE compared to values expected from the World Health Organization equation (1,541±112.6 vs 1,809±151.8 kcal; p=0.01). In contrast, the obese control children had measured REE within 1% of predicted (1,647±33.2 vs. 1,652±40.2; p=0.8). In a linear regression model, REE remained significantly lower than predicted after controlling for FFM. Conclusions Lower REE may be a factor contributing to obesity in children with craniopharyngioma. Further study is needed into the mechanisms for reduced energy expenditure in patients with craniopharyngioma.