Effect of growth hormone on the low level of growth hormone binding protein in idiopathic short stature.
OBJECTIVE
Growth hormone receptor status was assessed in children with idiopathic short stature by evaluating plasma growth hormone-binding protein before and under GH therapy.


METHODS
Among 22 children presenting idiopathic short stature, 15 were randomly selected to be treated with GH (1.2 IU/kg/week); they were studied before and under GH therapy. Untreated patients served as a control group for age and GH effect.


METHODS
Twenty-two prepubertal children, aged 5-11 years, were studied. They presented growth retardation of -2.8 +/- 0.1 SDS (mean +/- SEM). All had normal GH secretion and their mean IGF-I plasma level was normal.


METHODS
Growth hormone-binding protein was measured using high pressure liquid chromatography gel filtration. The specific binding of 125I-hGH to the growth hormone-binding protein was expressed as a percentage of the total radioactivity.


RESULTS
Specific binding of 125I-hGH to the high affinity growth hormone-binding protein was low with a mean +/- SEM value of 11.1 +/- 0.9% of radioactivity. In the treated group, growth hormone-binding protein increased significantly after 3 months of treatment; it reached 21.1 +/- 1.0% of radioactivity (mean +/- SEM) in the eight children who have been treated for 18 months. In the seven untreated children, the growth hormone-binding protein value increased to 16.2 +/- 1.1% after 18 months; this value is significantly lower than that found in the GH-treated children, demonstrating that the GH effect is greater than the age-related increase in the growth hormone-binding protein. A positive correlation was found between IGF-I plasma levels and growth hormone-binding protein and also between growth velocity and growth hormone-binding protein.


CONCLUSIONS
The low growth hormone-binding protein and the response to high doses of GH suggest partial GH resistance at the receptor level, in this group of children with idiopathic short stature.
Fontoura
M
M
Unité 30, Institut National de la Santé et de la Recherche Médicale, Hôpital Necker-Enfants Malades, Paris, France.
Mugnier
E
E
Brauner
R
R
Rappaport
R
R
Postel-Vinay
M C
MC
D002352:Carrier Proteins / Q000097:blood*; D002648:Child; D002675:Child, Preschool; D002851:Chromatography, High Pressure Liquid; D005260:Female; D006128:Growth / Q000502:physiology; D006130:Growth Disorders / Q000097:blood* / Q000188:drug therapy; D013006:Growth Hormone / Q000627:therapeutic use*; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000032:analysis; D008297:Male; D011986:Receptors, Somatotropin / Q000032:analysis / Q000378:metabolism*
D002352:Carrier Proteins; D011986:Receptors, Somatotropin; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone; C051815:somatotropin-binding protein