Context: GH treatment is approved for short children born SGA. The optimal dose is not yet established.

Objective: To develop a model for prediction of height at onset of puberty and of adult height (AH).

Design and Setting: Two GH studies in short SGA children.

Patients/Intervention: 150 SGA children with height SDS < -2, age 3, no signs of catch-up growth, available height at onset of puberty and at least one year of GH treatment prior to onset of puberty. In one study, patients were randomly assigned to either 0.033 or 0.067 mg/kg·day, in the other study all received 0.033 mg/kg·day. In 71 children, AH was reached.

Main outcome measures: Height SDS at onset of puberty and AH SDS.

Results: Determinants positively related to height SDS at onset of puberty were: height SDS at start, target height (TH) SDS and GH dose, whereas age at start and female gender were negatively related. Positively related to AH SDS were: height SDS and chronological age minus bone age (CA-BA) at start, TH SDS and GH dose, whereas serum IGFBP-3 SDS at start was negatively related. There was a significant interaction between GH dose and IGFBP-3 SDS, indicating a smaller GH dose effect for higher levels of IGFBP-3. The final model explained 57% of the variance in height SDS at onset of puberty and 41% of AH SDS.

Conclusion: The prediction model for height SDS at onset of puberty and AH SDS of short SGA children treated with GH provides useful information about the expected long-term growth. Because GH dosage is one of the determinants, the model aids in determining the optimal GH dose for each child.