Predictors of first-year growth response to a fixed-dose growth hormone treatment in children born small for gestational age: results of an open-label, multicenter trial in the United States

BACKGROUND: Previous studies of varied populations of non-uniformly defined children born small for gestational age (SGA) receiving different growth hormone (GH) regimens have found that GH treatment increased growth velocity and adult height and was safe. The GH dose was the major predictor of first year growth response. AIM: To identify pre- and within-treatment predictors of growth in well defined children born SGA treated with a fixed dose of GH. METHODS: 139 short, prepubertal children born SGA (i.e. birth weight and/or length > or =2 standard deviations below the mean) received Genotropin (rhGH) at 0.24 mg/kg/wk for 1 month then an additional 11 months at a dose of 0.48 mg/kg/wk, the FDA-approved dose of GH for children born SGA. RESULTS: Height improved significantly by month 3, with progressive improvement over the entire 12 months (median height SDS change of 0.78). Pretreatment predictors of growth included baseline bone age, IGFBP-3, total cholesterol, WBC and height SDS minus mid-parental height SDS. Within-treatment predictors of the change (Delta) height SDS at month 12 were the A height SDS at months 3 and 6 and growth velocity SDS at months 3 and 6. CONCLUSION: GH at 0.48 mg/kg/wk was well tolerated and improved growth in children born SGA; the Delta IGF-I was not predictive of the 12 month height SDS gain, while the Delta height SDS at 3 and 6 months were predictive. Underweight children grew as well as normal weight children, and both groups showed improved body composition following GH treatment.