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Height Velocity Targets for First Year Growth Hormone Responses in Short Children« Back to Volume 24, Issue 2, November 2008 - Table of Contents Recombinant human growth hormone (rhGH) has been used for treating a number of conditions. Several attempts have been made to define and predict GH response with the development of mathematical models, mostly in GH-deficient (GHD) patients. Such models do not account for the variability observed in GH responsiveness (or sensitivity) in different types of short stature. Therefore, the authors presented evidence-based data criteria for defining the GH responsiveness. Their aim was to provide clinicians with age-specific targets, considering the first year of treatment with standard daily doses of rhGH in prepubertal short children. Using data from the National Cooperative Growth Study (NCGS), GH response curves were constructed for the first year of treatment. All children were new to treatment and prepubertal. Data were collected from 4297 boys and 3061 girls with idiopathic/organic GHD, idiopathic short stature, and Turner syndrome. All data were cross-sectional, mean +1 SD for first year height velocity (HV) on rhGH were plotted (in cm) against subject age at onset of rhGH treatment, as well as the mean pre-treatment HV data. Height velocity plots of each category as a factor of age at baseline were developed. Mean –2 SD HV plots approximated the pre-treatment HV. The results were presented in a series of plots; these were primarily graphical. Interestingly, each graph contained the curve for the treatment growth velocity of different stages and types of patients (Figure). There was considerable variability in the response to therapy with rhGH in children receiving a standard weight-based dosing schedule. The wide range of clinical responsiveness to therapy may also denote a challenge to the traditional fixed weight-based dosing generally employed. It emphasized the importance of age at initiation of treatment. Another point of interest was the similarity of the growth response pattern across etiologies of short stature. These growth response curves should also be viewed as conservative and to include some limitations, ie, an unknown amount of non-compliance in all groups, GHD may be part of multiple pituitary deficiencies, etc. Nevertheless, it is suggested that these data offer the clinician a tool to assess progress of an individual patient within an evidence-based frame. Editor’s CommentThese data, derived from a large population study, are welcome and provide a context of the well known large variability in growth responses to rhGH therapy. The growth response graphs provided an additional but useful tool in contrast to numerous previous studies which proposed more theoretical and mathematical predictive approaches: prediction of the first year response to rhGH and prediction of adult height based on the first year growth response. These mathematical models were also derived from post-marketing long-term follow-up data, but they did not provide us with practical tools in clinical practice. The new growth response curves showing the first year of therapy may help evaluate the initial catch-up growth and the adjustment of rhGH doses after the first year of therapy. This could be performed in relation to age. In any case, they focus our attention on the first year of treatment and provide information which may turn out to be useful for the patient and the family, particularly in the group of idiopathic short stature patients and in those that may have compliance problems. Raphaël Rappaport, MD
« Back to Volume 24, Issue 2, November 2008 - Table of Contents
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Volume 26 Number 1
September 2010
www.GGHjournal.com
ISSN 1932-9032
