[Comparison of body fat measurement methods in children]

In the last decades the prevalence of overweight and obesity in pediatric population has increased. The cardiovascular diseases and type 2 diabetes are the consequences of fat tissue disturbances, so measurements of body fat in children might be expedient. Aim of the study was to compare the results of percent body fat measured on bioelectric impedance (BIA) and anthropometric method with reference method--dual-energy X-ray absorptiometry (DXA).

56 children at the age 6-18 years were included into the study. In all children height, weight, waist circumference and skinfolds were measured. BMI SDS and WC SDS were calculated. Percent body fat was estimated by DXA, BIA and anthropometric method. DXA was performed using total body program with Lunar Corporation apparatus BIA was made with an eight-electrode system. The anthropometric method was performed according to Slaughter's algorithm.

Correlation index between DXA and BIA was r2 = 0.83, and between DXA and Slaughter's algorithm - r2 = 0.83 (p < 0.001). All methods had high precision, but the differences between results obtained by three methods were observed. BIA and Slaughter's algorithm commonly lowered %BF, and underestimation become greater with values of this variable. The differences between results obtained by BIA and Slaughter's algorithm in comparison to DXA negatively correlated with BMI SDS and WC SDS. There was no relationship with patient age.

Usage of BIA or Slaughter's method for estimating percent body fat in children allows to obtain accurate results, but lower in comparison to results obtained on DXA. Because ofthis the same method must be used to monitor changes in %BF.