Growth hormone responsiveness: peak stimulated growth hormone levels and other variables in idiopathic short stature (ISS): data from the National Cooperative Growth Study.
OBJECTIVE
In children with idiopathic short stature (ISS), growth hormone (GH) response to a provocative test will be inversely related to the first year response to hGH and be a variable accounting for a degree of responsiveness.


BACKGROUND
Because high levels of GH are a characteristic of GH insensitivity, such as in Laron syndrome, it is possible that a high stimulated GH is associated with a lower first year height velocity among children diagnosed as having ISS.


METHODS
We examined the relationship between the peak stimulated GH levels in 3 ISS groups; GH >10 -<25, 25-40, and >40 ng/mL and the first year growth response to rhGH therapy. We also looked at 8 other predictor variables (age, sex, height SDS, height age, body mass index (BMI), bone age, dose, and SDS deficit from target parental height. Multiple regression analysis with the first year height as the dependent variable and peak stimulated GH was the primary endpoint. The predictive value of adding each of the other variables was then assessed.


RESULTS
Mean change in height velocity was similar among the three groups, with a maximum difference among the groups of 0.6 cm/yr. There was a small but statistically significant correlation (r=-0.12) between the stimulated GH and first year height velocity.


CONCLUSIONS
The small correlation between first year growth response and peak GH is not clinically relevant in defining GH resistance. No cut off level by peak GH could be determined to enhance the usefulness of this measure to predict response. Baseline age was the only clinically significant predictor, R-squared, 6.4%. All other variables contributed less than an additional 2% to the R-squared.
Moore
Wayne V
WV
Pediatric Endocrinology, Children's Mercy Hospital/University of Missouri-KC, Kansas City, MO 64108, USA. wmoore@cmh.edu
Dana
Ken
K
Frane
James
J
Lippe
Barbara
B
D001827:Body Height / Q000187:drug effects*; D002648:Child; D002657:Child Development / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005500:Follow-Up Studies; D006130:Growth Disorders / Q000097:blood / Q000188:drug therapy*; D019382:Human Growth Hormone / Q000009:adverse effects / Q000097:blood* / Q000627:therapeutic use*; D006801:Humans; D011159:Population Surveillance; D011994:Recombinant Proteins / Q000009:adverse effects / Q000097:blood / Q000627:therapeutic use; D014481:United States
D011994:Recombinant Proteins; D019382:Human Growth Hormone