Location of body fat and body size impacts DXA soft tissue measures: a simulation study.
OBJECTIVE
The aim of this study was to determine the ability of dual X-ray absorptiometry (DXA) to detect exogenous fat in men and women simulating typical sex-specific weight changes.


METHODS
A diverse sample including 29 elderly (52-83 years) and 61 young (18-40 years) individuals (45 women, 45 men) of varying body mass index (BMI; M+/-s.d.: 26.1+/-4.9 kg/m2, range=16.4-39 kg/m2).


METHODS
Whole body (WB) DXA scans (Hologic QDR 4500A) were completed with Scan 1 performed as a normal baseline scan, Scan 2 with 1 kg packet of lard placed on each thigh and Scan 3 with two 1 kg lard packets placed on the abdomen (men) or chest and abdomen (women).


RESULTS
Measurement error of fat mass (FM) was more pronounced in the trunk as lard packets were detected with 59% accuracy (error=0.82+/-0.42 kg, P<0.001), whereas 94% of thigh lard (error=0.11+/-0.45 kg, P<0.001) was determined to be FM, while the remainder in both conditions was determined to be mineral free lean mass. Initial FM (r=0.37, P<0.001) for thigh loading and trunk bone mineral content (r=0.30, P<0.01) for trunk-loaded conditions had the most impact on measurement error of WB FM.


CONCLUSIONS
Regional differences impact measurement error of simulated changes in FM with greater measurement error in the trunk compared to the thigh region and initial FM and higher levels of bone mineral content in the trunk region impacting error.
Valentine
R J
RJ
Department of Kinesiology and Community Health, University of Illinois at Urbana-Champaign, Urbana, IL, USA.
Misic
M M
MM
Kessinger
R B
RB
Mojtahedi
M C
MC
Evans
E M
EM
D015502:Absorptiometry, Photon / Q000379:methods* / Q000592:standards*; D000273:Adipose Tissue / Q000033:anatomy & histology* / Q000502:physiology; D050154:Adiposity / Q000502:physiology*; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001823:Body Composition / Q000502:physiology*; D004041:Dietary Fats; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012737:Sex Factors
D004041:Dietary Fats; C029310:lard