Determination of body composition in African-American children: Validationof bioelectrical impedence with dual energy X-ray absorptiometry

Body compositional differences between Black and White adults are well-know n, It has become increasingly apparent that these racial variations may beg in in childhood. Previously, our group validated tetrapolar bioelectrical i mpedance (BIA) measurements against H-2(O-18) dilution method to develop pr ediction formulas of fat free mass (FFM) in healthy White-American children : FFM = 0.524 Ht(2)/R + 0.415 Wt - 0.32, In the present study we used BIA t o establish a FFM prediction equation for forty African-American children ( 19 males and 21 females). Of the females, six were diagnosed with polycysti c ovary syndrome (PCOS) and were obese, FFM was determined by dual energy X -ray absorptiometry (DEXA), Impedence measurements by BIA showed a strong c orrelation with FFM determined by DEXA, In healthy Black children, FFM = 0. 84 Ht(2)/R + 1.10 with a standard error of estimate (SEE) of 1.47 kg (R-2 = 0.97), In Black females with PCOS, FFM = 0.62 Ht(2)/R + 0.21 Wt - 1.94 wit h a SEE of 1.43 kg (R-2 = 0.99). The observed differences in the prediction equations of FFM between White-American and African-American children unde rline the importance of using race-specific formulas in evaluating body com position. With the overall increase in rates of childhood obesity and more so in the Black race, BIA is an easy and useful tool for the assessment and follow up of body compositional changes with lifestyle interventions.