The Relationships of Pretreatment IGF-I SDS, Delay in Bone Age and Response to Recombinant Human Growth Hormone (rhGH) Therapy in Children with Growth Hormone Deficiency

ABSTRACT

PURPOSE: To assess whether pretreatment IGF-I SDS and pretreatmental bone age are useful indicators in the response of rhGH therapy in children with GH deficiency (GHD), the relationship between pretreatment IGF-I SDS, delay in bone age and the growth response during the first year of rhGH treatment was analyzed. METHODS: This study included 12 children with GHD. We measured IGF-I levels by RIA after acid-ethanol extraction at pretreatment and then calculated IGF-I SDS as follow SDS = (IGF-I- mean IGF-I for normal subjects of the same age and sex)/SD of IGF-I for normal subjects of the same age and sex. GH levels were measured by immunoradiometric assay. All patients were treated with rhGH, 0.1IU/kg daily, 6 times a week for 1 year. RESULTS: Twelve patients (6 males and 6 females), age distribution from 4 to 16 years, were studed. The data is reported as the mean +/- SD. Height SDS for chronologic age of the group as a whole as -3.6 +/- 1.0 and bone age was 8.2 +/- 3.4 years. Pretreatment height velocity (HV) was 4.0 +/- 1.7cm/yr and the HV during each 3 months of therapy were 10.1 +/- 4.5cm/yr, 9.6 +/- 4.5cm/yr, 8.5 +/- 4.3cm/yr and 7.8 +/- 1.3cm/yr, respectively and therefore the HV during the first year of rhGH therapy increased to 9.3 +/- 2.9cm/yr (P=0.002). Pretreatmental IGF-I SDS was -2.2 +/- 0.9 (-0.4~-3.6). A significant negative correlation between pretreatmental IGF-I SDS and incremental height gain was obtained (r=-0.40, P<0.05). The height velocity of the group whose pretreatmental IGF-I SDS was below -2 (n= 8) as a whole increased significantly from 3.5 +/- 1.8cm/yr to 10.3 +/- 2.9cm/yr (P=0.001). Pretreatmental bone age delay was 3.1 +/- 1.9 (0.5-7.8) years. The height velocity of the group whose pretreatmental bone age delay above 2 years (n=9) increased significantly from 4.1 +/- 1.1cm/yr to 9.7 +/- 2.9cm/yr (P=0.001). CONCLUSION: The height velocity of GH deficient children whose pretreatmental IGF-I SDS below -2 or pretreatmental bone age delay above 2 years increased significantly after rhGH therapy. It suggests that the pretreatmental IGF-I SDS and pretreatmental bone age may be significant indicatiors in the response of GH therapy in children with GHD.