Changes in body composition, resting energy expenditure, and thermic effect of food in short children on growth hormone therapy

Abstract

The effect of growth hormone (GH) treatment on body composition, resting energy expenditure (REE), and the thermic effect of food (TEF) was studied in 10 prepubertal boys (aged 6.2 to 9.5 years, with subnormal spontaneous GH secretion during the first 6 months of treatment [0.2 IU/kg · d]). Patients were studied before and at 2, 4 and 6 months after commencing treatment. Height and weight increased significantly during treatment (112.2 ± 4.5 to 117.2 ± 6.0 cm and 18.0 ± 2.8 to 20.8 ± 3.2 kg, respectively). Body fat percent decreased significantly (15.93% ± 4.08% to 11.97% ± 3.30%, P < .0002) but was not different at 4 and 6 months. Total body potassium (TBK) increased significantly (39.15 ± 5.77 to 48.70 ± 6.35 g, P < .001) during treatment. When correcting for the expected changes in body composition over time, height and weight were still shown to increase, fat percent decreased significantly, but TBK and mid-arm muscle circumference (MAMC) were not different from the expected values. REE increased significantly during treatment, but when it was expressed per TBK or corrected for the change in kilograms of fat-free body mass (FFBM), it increased only at 2 months and stabilized thereafter. The TEF was increased at 2 and 4 months of treatment and returned to pretreatment levels at 6 months of treatment. Substrate utilization as studied by indirect calorimetry pointed toward a significant protein-sparing effect during the first 4 months of treatment; this change tended to disappear in resting energy metabolism by 6 months of GH treatment. In conclusion, we have shown significant persistent changes in the body composition and transient changes in the energy metabolism of children during 6 months of GH treatment.