title: Comparison of total body potassium with other techniques for measuring lean body mass in men and women with AIDS wasting.
abstract: BACKGROUND
  Lean body mass is an important predictor of survival and functional status in patients with AIDS wasting. The bias between different techniques for assessing body composition in AIDS wasting is not known.
  
  
  METHODS
  We compared total body potassium (TBK) with fat-free mass (FFM) determined by dual-energy X-ray absorptiometry (DXA), bioelectrical impedance analysis (BIA), and skinfold-thickness measurement (SKF) in 132 patients (63 men, 69 women) with AIDS wasting (weight < 90% of ideal body weight, or weight loss > 10% of original, or both). None of the subjects exhibited clinical lipodystrophy. Comparisons were made by using different BIA equations.
  
  
  RESULTS
  Lean body mass determined by DXA was highly correlated with TBK in men (r = 0.79, P: < 0.0001) and women (r = 0.84, P: < 0.0001). FFM(BIA) and FFM(DXA) were significantly different (P: < 0.01 in men and P: < 0.0001 in women). The difference between FFM(DXA) and FFM(BIA) was significantly greater with greater weight and body fat, particularly in HIV-infected women (r = -0.39, P: = 0.001 for weight; r = -0.60, P: < 0.0001 for fat). The comparability of FFM and fat mass determined by DXA and BIA was dependent on the specific BIA equation used. Among men, no single BIA equation was more highly predictive of fat mass and FFM in comparison with DXA.
  
  
  CONCLUSIONS
  The differences between DXA, BIA, and SKF in the determination of fat mass and FFM are significant in patients with AIDS wasting. BIA overestimates FFM compared with DXA in those with greater body fat. Standard BIA equations may not accurately estimate FFM and fat mass in men and women with AIDS wasting.
authors.affiliation: Neuroendocrine Unit and the General Clinical Research Center, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA.
authors.forename: C
authors.initials: C
authors.lastname: Corcoran
authors.forename: E J
authors.initials: EJ
authors.lastname: Anderson
authors.forename: B
authors.initials: B
authors.lastname: Burrows
authors.forename: T
authors.initials: T
authors.lastname: Stanley
authors.forename: M
authors.initials: M
authors.lastname: Walsh
authors.forename: A M
authors.initials: AM
authors.lastname: Poulos
authors.forename: S
authors.initials: S
authors.lastname: Grinspoon
mesh_terms: D015502:Absorptiometry, Photon; D000328:Adult; D001823:Body Composition / Q000502:physiology*; D015992:Body Mass Index; D017097:Electric Impedance; D005260:Female; D019247:HIV Wasting Syndrome / Q000175:diagnosis*; D006801:Humans; D008297:Male; D011197:Potassium Radioisotopes; D012044:Regression Analysis; D012588:Scintillation Counting; D012885:Skinfold Thickness
chemical_list: D011197:Potassium Radioisotopes