Continued growth hormone (GH) treatment after final height is necessary to complete somatic development in childhood-onset GH-deficient patients.

Lean body mass (LBM), fat mass (FM), and total bone mineral content are significantly reduced in adult GHD subjects who had received pediatric GH. To test the hypothesis that continued GH therapy after final height is necessary to attain adult body composition, we performed a prospective, multinational, randomized, controlled, 2-yr study in patients who completed pediatric GH treatment at final height. Patients were randomized to GH at 25.0 microg/kg x d (pediatric dose; n = 58) or 12.5 microg/kg x d (adult dose; n = 59) or no GH treatment (control; n = 32). LBM and FM were measured by dual energy x-ray absorptiometry and were centrally evaluated. IGF-I, IGF-binding protein-3, and lipid concentrations were also measured centrally. During the 2 yr, GH-treated patients gained a significant amount of LBM compared with controls (P < 0.001), but the change with the higher pediatric dose (14.2 +/- 11.7%) was not different from that seen with the lower adult dose (12.7 +/- 9.4%; P = 0.970). Similarly, the decrease in FM was significantly (P = 0.029) influenced by treatment, but with no dose effect (adult dose, -7.1 +/- 22.8%; pediatric dose, -6.0 +/- 26.6%; P = 0.950). When the GH treatment effect was analyzed by gender, males gained 15.6 +/- 9.8% and 14.3 +/- 11.7% LBM (P = 0.711) and lost 12.4 +/- 22.2% and 11.0 +/- 27.1% FM (P = 0.921) with the low and high doses, respectively. Females gained 8.3 +/- 7.3% and 12.5 +/- 12.8% LBM with the two doses (P = 0.630), but increased their FM by 3.5 +/- 16.2% with the lower dose and lost only 1.2 +/- 23.2% FM with the higher dose (P = 0.325). A similar pattern was seen in IGF-I sd score; the 2-yr GH dose response was significantly higher with the pediatric than with the adult dose in females (P = 0.008), but not males (P = 0.790). The divergent pattern of change in LBM and FM in males and females is consistent with normal developmental sexual dimorphism and indicates that GH-dependent progress to target body composition continues after the age at which GH treatment is usually terminated. Dose requirements may have to be adjusted by gender, with females requiring a higher dose than males.

Effect of growth hormone (GH) treatment on bone in postpubertal GH-deficient patients: a 2-year randomized, controlled, dose-ranging study.

GH treatment in children with GH deficiency is frequently terminated at final height. However, in healthy individuals bone mass continues to accrue until peak bone mass is achieved. Because no prospective data specifically prove the role of GH in attainment of peak bone mass, we performed a multinational, controlled, 2-yr study in patients who had terminated pediatric GH at final height. Patients were randomized to: GH at 25.0 microg/kg x day (pediatric dose, n = 58) or 12.5 microg/kg x day (adult dose, n = 59), or no GH treatment (control, n = 32). Bone mineral content (BMC) and density were measured by dual-energy x-ray absorptiometry and evaluated centrally. Laboratory measurements were also performed centrally. After 2 yr, significant increases were seen with both GH treatments, compared with control in bone-specific alkaline phosphatase (P = 0.004) and type I collagen C-terminal telopeptide:creatinine ratio (P < 0.001), but there were no significant dose effects. Total BMC increased by 9.5 +/- 8.4% in the adult dose group, 8.1 +/- 7.6% in the pediatric dose group, and 5.6 +/- 8.4% in controls (analysis of covariance, P = 0.008), with no significant GH dose effect. BMC increased predominantly at the lumbar spine (11.0 +/- 10.6%, P = 0.015) rather than at the femoral neck or hip. In contrast, a significant dose-dependent increase was seen in IGF-I concentrations (adult dose: 114.5 +/- 119.4 microg/liter; pediatric dose: 178.5 +/- 143.7 microg/liter; P = 0.023). There were no gender-related differences in BMC changes with either dose, whereas the IGF-I increase was significantly higher with the pediatric than with the adult dose in females (P < 0.001) but not males (P = 0.606). In summary, reinstitution of GH replacement after final height in severely GH-deficient patients induced significant progression toward peak bone mass. Although there was a by-gender dose effect on IGF-I concentration, the treatment effect on bone was obtained in both males and females with the adult GH dose regimen.