In Reply We thank Kelly et al for their suggestion to investigate the accuracy of the triponderal mass index (TMI; weight/height3)1 vs body mass index in estimating visceral adipose tissue (VAT) percentage in adolescents. We agree with the authors that estimating VAT may better identify adolescents at risk for insulin resistance and dyslipidemia, leading to better risk stratification.2 While the National Health and Nutrition Examination Survey data set includes VAT data as measured by the Hologic dual-energy x-ray absorptiometry (DXA) system in adults, it does not include VAT data for adolescents. To date, the US Food and Drug Administration has approved the Hologic DXA software to report VAT in only adults. There have been several studies that have compared manually derived DXA estimates of VAT with computed tomography measurements of VAT.3-5 These estimations rely on assumptions involving the distribution of fat in adults, which may not be valid before puberty. As evidence, the correlations between manually derived DXA estimates and computed tomography measurements are indeed substantially lower in adolescents than in adult populations.2,6 Nonetheless, there are computed tomography and magnetic resonance imaging studies that can be pooled to provide a preliminary indication of how well TMI and other indices, such as body mass index, predict VAT in adolescents. Moreover, as technology evolves, we anticipate that DXA-derived estimates of VAT in adolescents will improve in accuracy and eventually be approved by the US Food and Drug Administration. In summary, a full-scale analysis similar to the one we performed relating TMI to total body fat in adolescents1 is not yet feasible for VAT, but we look forward to it being a possibility in the near future.
Peterson CM, Thomas DM, Heymsfield SB. The Use of Tri-Ponderal Mass Index and Other Indices in Estimating Visceral Body Fat Percentages in Adolescents—Reply. JAMA Pediatr. 2017;171(12):1228. doi:10.1001/jamapediatrics.2017.3447
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