Body composition assessment in paediatric patients. Validation of new methods of body composition measurements in obese children

Identifier:  TDX:2953

Handle: https://hdl.handle.net/20.500.11797/TDX2953

Authors:  Gutiérrez Marín, Desirée

Abstract:
Obesity is defined as an excess of fat in the body but it is usually diagnosed by methods which cannot actually measure or estimate the adipose tissue of the body, i.e. body mass index (BMI). There are many existing techniques which can differentiate body compartments in vivo and then, fat can be estimated with a relative high level of accuracy, i.e. dual energy X-ray absorptiometry (DXA), air-displacement plethysmography (ADP), isotopic dilutions, multi-component models, among others. The gold standard method to assess body composition in vivo is the four-component model. However, these techniques have some limitations, and mainly, all of them are expensive and implausible for clinical practice. Bioelectrical impedance analysis (BIA) has been proposed as a suitable technique to assess body composition in a wide range of populations, including obese children. However, there are research evidences that showed a poor accuracy of BIA body composition assessments in this population. Our results showed that this lack of accuracy might be due to the assumption of constant values of the fat-free mass properties, hydration and density, when assessing body composition by 2-component based techniques (e.g. ADP and BIA). Considering this fact, this work proposed two new methods to assess body composition in obese children: the first one suggested that using calculated values of the density of the fat-free mass, with the new predictive equation, instead the published constant values when assessing body composition by 2-component based techniques (e.g. ADP) improves the accuracy of the technique; the second method shows a new equation to calculate the fat-free mass from whole-body impedance measurements, which improves the accuracy of the impedance analysers manufacturer’s equations in obese population.