To examine whether supplemental nutrition augments the anabolic actions of growth hormone (GH) in boys with constitutional delay of growth and maturation (CDGM).

We conducted a randomized, controlled trial at an outpatient clinical research center. Subjects were 20 prepubertal boys (age, 9.3 ± 1.3 years) with CDGM (height standard deviation score, –2.0 ± 0.5; bone age delay, 1.8 ± 0.8 years; body mass index standard deviation score, –1.2 ± 1.0; peak stimulated GH, 15.7 ± 7.7 ng/mL), who were randomized (n = 10/group) to 6 months observation or daily nutritional supplementation, followed by additional daily GH therapy in all for another 12 months. t tests and repeated measures analyses of variance compared energy intake, total energy expenditure (TEE), growth, hormones, and nutrition markers.

Energy intake was increased at 6 months within the nutrition group (P = .04), but not the observation group, and TEE was not statistically different within either group at 6 months. Addition of 6 months GH resulted in higher energy intake and TEE in the GH/nutrition group at 12 months (P < .01), but not in the GH group versus baseline. Height, weight, lean body mass, hormones, and nutrition markers increased comparably in both groups throughout 18 months.

Boys with CDGM use energy at an accelerated rate, an imbalance not overcome with added nutrition. GH therapy increases growth comparably with or without added nutrition in these patients.