ESPE Abstracts (2018) 89 P-P2-051

Bone Marrow Adiposity and IGF System in Obese Children and Adolescents

Emiliana Darrigo, Soraya Sader, Thais Siena, Marcelo Nogueira-Barbosa, Jorge Elias Jr., Rodrigo Custódio, Ivan Ferraz, Raphael Liberatore Jr., Luiz Del Ciampo, Francisco José Albuquerque de Paula & Carlos Martinelli Jr

Ribeirao Preto Medical School, University of São Paulo, Ribeirão Preto-SP, Brazil

Background: Body weight has a close correlation with bone mass in humans and high fracture rates has been reported in both obese and underweighted individuals. It is not clear the role of bone marrow adiposity (BMA) and the IGF system in this process.

Aim: The aim of this study was to analyze bone composition and BMA in obese and non-obese children/adolescents and correlate them with the expression of the IGF type-1 receptor (IGF1R) in peripheral lymphocytes and serum concentrations of IGF-I and IGFBP-3.

Methods: Thirty subjects aged 8 to 18 years old were enrolled and divided into 2 age-matched groups: obese (n=15) and non-obese (n=15). These groups were submitted to anthropometric evaluation, lumbar spine (L1-L4 and L3) and total body bone densitometry and lumbar spine and total abdominal magnetic resonance. Blood sample was collected at the same moment for IGF-I, IGFBP-3, IGF1R and biochemical evaluation.

Results: BMA was similar in the obese group and non-obese. Bone mineral density (BMD) was higher in the obese group compared to non-obese even after adjustment for bone age or volumetric densitometry analysis. No correlation was found between BMA and BMD. A positive correlation between BMD and both fat mass and lean mass was observed in obese patients. On the other hand, in the non-obese group a positive correlation was found only between BMD and fat mass. IGF-I and IGFBP-3 concentrations were similar in both groups. No difference was observed regarding IGF1R gene expression. No correlation was observed between BMA or BMD and IGF1R gene expression, serum IGF-I or IGFBP-3 concentrations.

Conclusion: It was shown that there is no difference in BMA between obese and non-obese children/adolescents. A possible role for the IGF system in the BMA determination seems to be more important at paracrine/autocrine level. Body composition, especially fat mass, seems to be important in determining bone mass in obese children/adolescents.