Objectives: To investigate the effects of growth hormone (GH) treatment, using a dose-adjustment regimen based on serum insulin-like growth factor (IGF)-I concentrations, in adult Japanese hypopituitary patients with GH deficiency.
Study design: Japanese patients who had initially been administered GH (n = 31) or placebo (n = 28) in a 24-week double-blind study received individualized GH treatment in an open-label study for 48 weeks. Body composition from dual-energy X-ray absorptiometry (DXA) and serum IGF-I, IGF-binding protein 3 (IGFBP-3) and lipid levels were determined centrally.
Results: Significant increases in lean body mass (4.5%) and decreases in fat mass (-10.5%) were observed in the group that received individualized GH doses in the present open-label study following placebo in the double-blind study. This was comparable with the changes observed in these parameters (4.7 and -9.2%, respectively) with fixed-dose GH treatment in the double-blind study; this latter group maintained these improvements throughout the open-label study. Individualized dose adjustment allowed for more moderate dose increases than the fixed-dose titration method. Individualized dosing also resulted in a lower mean dose for adult-onset compared with childhood-onset GH-deficient patients (0.032+/-0.019 versus 0.061+/-0.023 mg/kg per week for patients treated with GH for 48 weeks in the open-label study following placebo in the double-blind study). Dosing patterns in the two groups were paralleled by the changes in IGF-I and IGFBP-3. The incidence of oedema and cases with high IGF-I level were less frequent under the IGF-I controlled regimen compared with those during the fixed-dose titration method.
Conclusion: Individualized GH administration based on IGF-I levels was safe and effective. This regimen demonstrated differences in dose requirements between adult- and childhood-onset patients. An individualized dose regimen is recommended in adult Japanese GH-deficient patients.