DXA Body Composition Analysis in Obesity

Body composition analysis was assessed by dual energy X-ray absorptiometry (DXA) (GE Healthcare Lunar Prodigy Advance, GE Medical Systems, Milan, Italy), which is said to be the gold standard for body composition measurements in obese patients. Subjects were instructed to avoid excess physical effort in the 24 h before the analysis. The DXA measurement was performed in the morning, after a night's rest, fasting. Subjects were instructed in detail regarding the measurement procedure. During the procedure, patients wore cotton T-shirts, shorts, and socks with no metal, rubber, and plastic objects, and laid on the DXA table supine and motionlessly. The same trained operator positioned the subjects, performed the DXA scans, and executed the analysis according to the operator's manual, using the standard analysis protocol. The standard scan mode (for moderately obese subjects) or the thick scan mode (for extremely obese subjects), with absorbed radiation doses of 0.4 μGy and 0.8 μGy, respectively, were used. The intrasubject and intersubject coefficients of variation (CV% = 100 × standard deviations [SD]/mean) ranged from 1% to 5%. The coefficient of variation for the bone mass measurements was <1%. Anthropometric and DXA measurements are described in detail in our previous studies.^{[16 (link),30 (link),31 (link)]}