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[IGF-I sensitivity in small for gestational age children]
Rossana Román R1, Germán Iñíguez V, Teresa Salazar C
1Instituto de Investigaciones Materno Infantil, Universidad de Chile, Santiago, Chile.
Insights
Small for gestational age (SGA) children lacking catch-up growth (CUG) may have reduced insulin-like growth factor 1 (IGF-I) sensitivity. This study found decreased pituitary sensitivity to IGF-I in some SGA children without CUG.
Area of Science:
- Pediatric Endocrinology
- Growth Hormone Physiology
- Insulin-like Growth Factor Signaling
Context:
- Small for gestational age (SGA) is a condition where infants are born smaller than expected based on gestational age.
- Catch-up growth (CUG) is a period of accelerated growth that may occur after a period of slowed growth.
- Reduced sensitivity to insulin-like growth factor 1 (IGF-I) has been hypothesized as a cause for the lack of CUG in SGA children.
Purpose:
- To investigate the sensitivity to IGF-I in prepubertal SGA children.
- To measure nocturnal growth hormone (GH) profiles before and after IGF-I administration to assess pituitary response.
Summary:
- Thirty-four prepubertal SGA children (4-11 years) were studied, with 23 exhibiting CUG and 11 not.
- Nocturnal GH levels were measured at baseline and after administration of the IGF-I + IGFBP-3 complex (Somatokine).
- While GH levels decreased in all SGA children post-Somatokine, 3 of 11 SGA children without CUG showed an increase in GH AUC, suggesting potentially decreased pituitary sensitivity to IGF-I in this subgroup.
Impact:
- Findings suggest that impaired pituitary sensitivity to IGF-I may contribute to the failure of catch-up growth in a subset of SGA children.
- This research highlights a potential mechanism underlying growth disturbances in SGA individuals.
- Further investigation into IGF-I signaling pathways could inform therapeutic strategies for SGA 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).
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 (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.
