Sensibilidad a IGF-I en niños pequeños para la edad gestacional
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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). Aim: 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). Patients and 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 (SomatokineÂ®). Results: At the time of the study, the Z scores for height among children with and without CUG were -1.55 Â± 0.22 and -3.24 Â± 0.28, respectively (p <0.0001). There were no statistical differences between CUG + vs CUG- patients in mean basal GH (6.6 Â± 0.5 and 5.6 Â± 0.6 ng/ml, respectively). After SomatokineÂ® 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 SomatokineÂ® administration, whereas 3 out of 11 SGA children without CUG had an increase in their mean GH AUC in response to SomatokineÂ®. Conclusions: These findings suggest that pituitary sensitivity to IGF-I may be decreased in some SGA children without CUG.