Context: Although growth hormone (GH) has been used to treat short stature in GH deficiency (GHD) and other conditions for 40+ years, criteria for satisfactorily defining targets for GH responsiveness have never been developed.

Objective: To present the first year growth expressed as height velocity for prepubertal boys and girls with idiopathic GH deficiency (IGHD), organic GH deficiency (OGHD), idiopathic short stature (ISS), or Turner syndrome (TS) from Genentech's National Cooperative Growth Study (NCGS) in order to derive age specific targets for GH responsiveness for each etiology and gender.

Design and Population: Using data from NCGS we constructed curves of response to GH during the first year of treatment with standard daily doses in naïve-to-treatment prepubertal children with IGHD (2323 males/842 females), OGHD (582 males/387 females), ISS (1392 males/465 females) or TS (1367 females).

Main outcome measure: For each category, mean pre-treatment and mean ±1 and ± 2 SD for the first year height velocities (HV) on GH were assessed. Mean and mean ± 1 SD for HV were plotted versus age at baseline (initiation of GH treatment) and compared to mean pre-treatment HV.

Results: HV plots for each category, as a factor of age at baseline are presented. Mean -2 SD HV plots approximated the pre-treatment HV.

Conclusion: Using baseline age- and gender-specific targets will assist clinicians in assessing a patient's first year growth response. We propose that HV below the mean – 1 SD on these plots be considered a "poor" response. These curves may be used to identify patients who may benefit from GH dose adjustment, assessment of compliance issues, or to challenge the original diagnosis.