Estimation of percent body fat based on anthropometric measurements in children and adolescents with congenital adrenal hyperplasia due to 21-hydroxylase deficiency

Abstract

Congenital adrenal hyperplasia due to 21-hydroxylase deficiency is associated with a high risk for obesity. Anthropometric measures are simple and inexpensive methods to assess body fat. However, the accuracy of alternative methods in these patients is unknown. This study aim to develop and evaluate the accuracy of predictive anthropometric equations in the estimation of percent body fat in individuals with congenital adrenal hyperplasia due to 21-hydroxylase deficiency. A total of 31 female and 22 male patients, aged 7-20 years, were evaluated. Dual-energy X-ray absorptiometry was used as the reference method for body fat, and anthropometric measurements were performed. Three new predictive equations showed similar results: Equation (1) (R² = 0.85; SEE = 2.89%), Equation (2) (R² = 0.86; SEE = 2.82%), and Equation (3) (R² = 0.86; SEE = 2.81%). Internal cross-validation procedures showed a high R² (range, 0.84-0.85) and low SEE (<3%). The limits of agreement ranged from -5.6% to 5.6% and no trend was observed. In children and adolescents with congenital adrenal hyperplasia due to 21-hydroxylase deficiency, three new predictive equations were validated for the estimation of percent body fat, with dual-energy X-ray absorptiometry as the reference method.