Growth response to growth hormone therapy in patients with different degrees of growth hormone deficiency.

Abstract

Growth response to GH therapy in prepubertal patients with idiopathic GH deficiency (GHD) was analyzed in terms of the chronological age at the start of GH treatment and the GH secretory capacity, by using the large database provided by the International Cooperative Growth Study (ICGS) Japan. 1192 patients, aged from 3 to 10 years were divided into three groups with the following maximum GH values in GH stimulation tests: Group A: both < or = 5 ng/ml, group B: both 5-10 ng/ml, group C: one > 10 ng/ml. Analysis of age-related growth response using with delta height SDS (delta height SDS) as a response variable revealed that the group A patients responded better to GH, while there was no differences between the other groups. Simple and multiple regression analysis showed that IGF-I and chronological age (CA) negatively correlated with growth response, and target height SDS-height SDS positively correlated. These three most important predictors accounted for 49% of the variation in the growth response in group A, whereas six variables such as CA, frequency of GH injection, % overweight, GH dose, target height-height SDS, and pretreatment height velocity SDS accounted for only 28% of those in groups of B and C. These results lead us to conclude that growth response to GH is related to the degree of GH impairment with its cut-off level of 5 ng/ml. From these findings it might be suggested that treatment regimen should be tailored to individual requirements according to the degree of GHD.