[IGF-I sensitivity in small for gestational age children].
BACKGROUND
The lack of catch up growth (CUG) in small for gestational age (SGA) children may be related to a reduced sensitivity to insulin growth factor 1 (IGF-I).


OBJECTIVE
To assess the sensitivity to IGF-I in small for gestational age children, measuring basal and post IGF-I nocturnal profile of growth hormone (GH).


METHODS
We studied 34 prepubertal SGA children aged 4 to 11 years. Twenty three had CUG and 11 did not have CUG. As an IGF-I sensitivity test, nocturnal GH levels were measured every 20 minutes from 23:00 h to 07:00 h, both under baseline conditions and after the administration of a subcutaneous bolus of 1 mg/kg/body weight of the IGF-I + IGFBP-3 complex (Somatokine).


RESULTS
At the time of the study, the Z scores for height among children with and without CUG were -1.55 +/- 0.22 and -3.24 +/- 0.28, respectively (p <0.0001). There were no statistical differences between CUG + vs CUG- patients in mean basal GH (6.6 +/- 0.5 and 5.6 +/- 0.6 ng/ml, respectively). After Somatokine administration, mean GH, and the mean GH area under the curve (AUC) decreased significantly in both groups. However, mean overnight GH AUC decreased in all SGA children with CUG, after Somatokine administration, whereas 3 out of 11 SGA children without CUG had an increase in their mean GH AUC in response to Somatokine.


CONCLUSIONS
These findings suggest that pituitary sensitivity to IGF-I may be decreased in some SGA children without CUG.
Román R
Rossana
R
Instituto de Investigaciones Materno Infantil, Universidad de Chile, Santiago, Chile.
Iñíguez V
Germán
G
Salazar C
Teresa
T
Avila A
Alejandra
A
Barrera P
Alvaro
A
Fuentes G
Ariel
A
Mericq G
Verónica
V
Gunn
Ronald D
RD
Cassorla G
Fernando
F
D015415:Biomarkers / Q000097:blood; D001827:Body Height; D002648:Child; D002675:Child, Preschool; D005260:Female; D013006:Growth Hormone / Q000097:blood* / Q000378:metabolism; D006801:Humans; D015592:Immunoradiometric Assay; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age / Q000097:blood* / Q000254:growth & development; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000097:blood* / Q000378:metabolism; D007334:Insulin-Like Growth Factor I / Q000032:analysis* / Q000378:metabolism; D008297:Male; D011247:Pregnancy; D011993:Recombinant Fusion Proteins / Q000008:administration & dosage*
D015415:Biomarkers; D018972:Insulin-Like Growth Factor Binding Protein 3; D011993:Recombinant Fusion Proteins; C475619:somatoKine; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone