Energy expenditure in obesity associated with craniopharyngioma

Abstract

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 body mass 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.

Fig. 1

REE measured by indirect calorimetry (white) versus REE predicted by the WHO formula (gray) in obese control subjects and obese craniopharyngioma patients. NS nonsignificant; *p=0.01

Fig. 2

ΔREE or the difference between predicted REE and measured REE in obese control children and children with obesity and craniopharyngioma

Fig. 3

Association between fat-free mass and measured REE in obese craniopharyngioma patients (filled squares, solid line) and obese controls (unfilled circles, dashed line)