Growth hormone bioactivity, insulin-like growth factors (IGFs), and IGF binding proteins in obese children

Radetti, G.; Bozzola, M.; Pasquino, B.; Paganini, C.; Aglialoro, A.; Livieri, C.; Barreca, A.

« Previous Next »Metabolism - Clinical and Experimental
Volume 47, Issue 12 , Pages 1490-1493, December 1998

Growth hormone bioactivity, insulin-like growth factors (IGFs), and IGF binding proteins in obese children

G. Radetti
- Address reprint requests to G. Radetti, MD, Department of Paediatrics, Regional Hospital of Bolzano, via L Boehler n^o 5, 39100 Bolzano, Italy.
- Department of Paediatrics, Regional Hospital of Bolzano, Bolzano, Italy
- Department of Paediatrics, University of Pavia, Pavia, Italy
- Department of Endocrinology and Metabolism, University of Genova, Genova, Italy
M. Bozzola
- Department of Paediatrics, Regional Hospital of Bolzano, Bolzano, Italy
- Department of Paediatrics, University of Pavia, Pavia, Italy
- Department of Endocrinology and Metabolism, University of Genova, Genova, Italy
B. Pasquino
- Department of Paediatrics, Regional Hospital of Bolzano, Bolzano, Italy
- Department of Paediatrics, University of Pavia, Pavia, Italy
- Department of Endocrinology and Metabolism, University of Genova, Genova, Italy
C. Paganini
- Department of Paediatrics, Regional Hospital of Bolzano, Bolzano, Italy
- Department of Paediatrics, University of Pavia, Pavia, Italy
- Department of Endocrinology and Metabolism, University of Genova, Genova, Italy
A. Aglialoro
- Department of Paediatrics, Regional Hospital of Bolzano, Bolzano, Italy
- Department of Paediatrics, University of Pavia, Pavia, Italy
- Department of Endocrinology and Metabolism, University of Genova, Genova, Italy
C. Livieri
- Department of Paediatrics, Regional Hospital of Bolzano, Bolzano, Italy
- Department of Paediatrics, University of Pavia, Pavia, Italy
- Department of Endocrinology and Metabolism, University of Genova, Genova, Italy
A. Barreca
- Department of Paediatrics, Regional Hospital of Bolzano, Bolzano, Italy
- Department of Paediatrics, University of Pavia, Pavia, Italy
- Department of Endocrinology and Metabolism, University of Genova, Genova, Italy

Received 21 January 1998; accepted 18 June 1998.

Abstract

In obese children, both spontaneous and stimulated growth hormone (GH) secretion are impaired but a normal or increased height velocity is usually observed. This study was undertaken to explain the discrepancy between impaired GH secretion and normal height velocity. We evaluated the GH bioactivity (GH-BIO), GH serum level by immunofluorimetric assay (GH-IFMA), insulin-like growth factor-I (IGF-I), IGF-II, and IGF binding protein-1 (IGFBP-1), IGFBP-2, and IGFBP-3 in 21 prepubertal obese children (13 boys and eight girls) aged 5.7 to 9.4 years affected by simple obesity and in 32 (22 boys and 10 girls) age- and sex-matched normal-weight controls. The results were as follows (obese versus [v] controls): GH-IFMA, 4.84 ± 3.54 v 23.7 ± 2.04 μg/L (P < .001); GH-BIO, 0.60 ± 0.45 v 1.84 ± 0.15 U/mL (P < .001); IGF-I, 173.8 ± 57.2 v 188.6 ± 132.6 ng/mL (nonsignificant); IGF-II, 596.1 ± 139.7 v 439.3 ± 127.4 ng/mL (P < .001); IGFBP-1, 23.25 ± 14.25 v 107 ± 165.7 ng/mL (P < .05); IGFBP-2, 44.37 ± 62.18 v 385.93 ± 227.81 ng/mL (P < .001); IGFBP-3, 3.31 ± 0.82 v 2.6 ± 0.94 μg/mL (P < .05); and IGFs/IGFBPs, 1.32 ± 0.32 v 1.07 ± 0.34 (P < .05). In conclusion, in prepubertal obese children, not only immunoreactive but also bioactive GH concentrations were low. In these subjects, therefore, nutritional factors and insulin may contribute to sustain normal growth also by modulating several components of the IGF-IGFBP system.