The efficacy and safety of recombinant growth hormone in children with idiopathic short stature (two-year experience)

This study was designed to evaluate the efficacy and safety of the treatment of children with idiopathic short stature using recombinant growth hormone (rGH); in addition, the factors influencing its therapeutic efficiency were analysed. A total of 93 patients aging from 3 to 12 years were available for the observation. They were divided into three groups. The children in group 1 (n=38 ) were given rGH at a dose of 0.033 mg/kg/24 hours and in group 2 (n=18 ) at 0.05 mg/kg/24 hr; the control group 3 was comprised of 37 children. The duration of therapy was 6 months in 56 children, 12 months in 41, 18 months in 24, and 24 months in 18 children. The end points of the study were bone age variations; dynamics of insulin-like growth factor-1 levels; characteristics of carbohydrate, lipid, and phosphorus-calcium metabolism; hepatic, renal, and thyroid function. The growth rate within the first year after the onset of the treatment increased from 4.5±1.2 to 7.9±1.5 cm/year in group 1 (0.033 mg/kg/24 hours) and from 9.1±1.5 cm/year in group 2 (0.05 mg/kg/24 hr). In the second year, the growth rate under effect of the same GH doses was 7.1±1.4 and 7.9±1.6 cm/year respectively. The total growth rate ΔSDS for the first year of therapy was 0,56±0,28 (0,033 mg/kg/24 hr) and 0,71±0,22 (0,05 mg/kg/24 hr), the respective ΔSDS values in the second year were 0,94±0,29 and 1,06±0,67. Neither the growth rate nor the failure to thrive changed significantly in the control group. The growth rate in the treated children correlated with their age at the onset of therapy (r = –0.28, p= –0.045; n=56) and the dose of GH (r=0.32, p –2ΔSDS) 6 months after the beginning of therapy, 30% and 37% after 1 and 2 years respectively. None of the patients in the control group showed the normal growth. Some of them underwent accelerated bone maturation, and their growth prognosis (calculated according to Bayley-Pinneau) was improved. The IGF-1 level in the treated patients increased within the normal range but did not correlate with the efficacy of therapy. Nor were apparent changes recorded in the characteristics of carbohydrate, lipid, and phosphorus-calcium metabolism. It is concluded that the growth-stimulating treatment of children with idiopathic short stature using rGH at a dose range from 0.033 to 0.05 mg/kg/24 hours significantly increased the growth rate and dynamics. The main factors determining the therapeutic efficacy of rGH are the age of the patients at which the treatment is initiated and the calculated rGH dose.