Context: Children with constitutional delay of growth and maturation (CDGM) tend to be thin and have a growth pattern reminiscent of nutritional insufficiency.

Objectives: To compare differences in nutrition, body composition, bone mineral density, resting and total energy expenditure (REE/TEE) in boys with CDGM and controls. We hypothesized that an imbalance between energy intake and expenditure may contribute to the pathogenesis of CDGM.

Design: Observational, cross-sectional study.

Patients: 36 boys (8-17y): 12 with CDGM (short stature, delayed bone age and puberty, no other pathology), 12 height-matched (pre- or early-pubertal) and 12 age-matched (pubertal) healthy controls.

Setting: Outpatient clinical research center

Main Outcome Measures: Doubly-labeled water studies (TEE); serum nutritional/hormonal markers, DEXA, dietary analysis, and indirect calorimetry (REE).

Results: Nutritional markers were comparable among the groups. CDGM subjects had lower bone mineral density than age-controls (P < 0.01), but comparable with height-controls. Even though REE did not differ between groups, CDGM subjects had 25% higher caloric intake adjusted for fat-free mass (FFM) than height-controls (P < 0.05) and 78% higher caloric intake/kgFFM compared with age-controls (P < 0.00001). CDGM subjects had 46% (P < 0.05) and 91% (P < 0.001) higher TEE/kgFFM than height- and age-controls, respectively. CDGM subjects had lower IGF-1 and testosterone than age-controls (P < 0.001), but comparable with height-controls.

Conclusions: Boys with CDGM have higher rates of overall energy expenditure compared with age- and size-matched controls. This increased metabolism may result in impaired tempo of growth. Further studies are needed to determine whether augmenting nutrition to match their energy needs (with or without hormonal therapy) can improve linear and ponderal growth in patients with CDGM.