Adult Height after Long-Term, Continuous Growth Hormone (GH) Treatment in Short Children Born Small for Gestational Age: Results of a Randomized, Double-Blind, Dose-Response GH Trial

The GH dose-response effect of long-term continuous GH treatment on adult height (AH) was evaluated in 54 short children born small for gestational age (SGA) who were participating in a randomized, double-blind, dose-response trial. Patients were randomly and blindly assigned to treatment with either 3 IU (group A) or 6 IU (group B) GH/m(2).d ( approximately 0.033 or 0.067 mg/kg.d, respectively). The mean (+/-SD) birth length was -3.6 (1.4), the age at the start of the study was 8.1 (1.9) yr, and the height SD score (SDS) at the start of the study -3.0 (0.7). Seventeen of the 54 children were partially GH deficient (stimulated GH peak, 10-20 mU/liter). Fifteen non-GH-treated, non-GH-deficient, short children born SGA, with similar inclusion criteria, served as controls [mean (+/-SD) birth length, -3.3 (1.2); age at start, 7.8 (1.7) yr; height SDS at start, -2.6 (0.5)]. GH treatment resulted in an AH above -2 SDS in 85% of the children after a mean (+/-SD) GH treatment period of 7.8 (1.7) yr. The mean (SD) AH SDS was -1.1 (0.7) for group A and -0.9 (0.8) for group B, resulting from a mean (+/-SD) gain in height SDS of 1.8 (0.7) for group A and 2.1 (0.8) for group B. No significant differences between groups A and B were found for AH SDS (mean difference, 0.3 SDS; 95% confidence interval, -0.2, 0.6; P > 0.2) and gain in height SDS (mean difference, 0.3 SDS; 95% confidence interval, -0.1, 0.7; P > 0.1). When corrected for target height, the mean corrected AH SDS was -0.2 (0.8) for group A and -0.4 (0.9) for group B. The mean (+/-SD) AH SDS of the control group [-2.3 (0.7)] was significantly lower than that of the GH-treated group (P < 0.001). Multiple regression analysis indicated the following predictive variables for AH SDS: target height SDS, height SDS, and chronological age minus bone age (years) at the start of the study. GH dose had no significant effect. In conclusion, long-term continuous GH treatment in short children born SGA without signs of persistent catch-up growth leads to a normalization of AH, even with a GH dose of 3 IU/m(2).d ( approximately 0.033 mg/kg.d).