title: Accuracy of eight-polar bioelectrical impedance analysis for the assessment of total and appendicular body composition in peritoneal dialysis patients.
abstract: OBJECTIVE
  To establish the accuracy of bioelectrical impedance analysis (BIA) for the assessment of total and appendicular body composition in peritoneal dialysis (PD) patients.
  
  
  METHODS
  Cross-sectional study.
  
  
  METHODS
  University Nephrology Clinic.
  
  
  METHODS
  In all, 20 PD patients and 77 healthy controls matched for gender, age and body mass index.
  
  
  METHODS
  Whole-body fat-free mass (FFM) and appendicular lean tissue mass (LTM) were measured by dual-energy X-ray absorptiometry. Resistance (R) of arms, trunk and legs was measured by eight-polar BIA at frequencies of 5, 50, 250 and 500 kHz. Whole-body resistance was calculated as the sum of R of arms, trunk and legs. The resistance index (RI) was calculated as the ratio between squared height and whole-body or segmental R.
  
  
  RESULTS
  RI at 500 kHz was the best predictor of FFM, LTM(arm) and LTM(leg) in both PD patients and controls. Equations developed on controls overestimated FFM and LTM(arm) and underestimated LTM(leg) when applied to PD patients. Specific equations were thus developed for PD patients. Using these equations, the percent root mean-squared errors of the estimate for PD patients vs controls were 5 vs 6% for FFM, 8 vs 8% for LTM(arm) and 7 vs 8% for LTM(leg).
  
  
  CONCLUSIONS
  Eight-polar BIA offers accurate estimates of total and appendicular body composition in PD patients, provided that population-specific equations are used.
authors.affiliation: Cattedra di Nefrologia, Università di Modena e Reggio Emilia, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Medici
authors.forename: C
authors.initials: C
authors.lastname: Mussi
authors.forename: A L
authors.initials: AL
authors.lastname: Fantuzzi
authors.forename: M
authors.initials: M
authors.lastname: Malavolti
authors.forename: A
authors.initials: A
authors.lastname: Albertazzi
authors.forename: G
authors.initials: G
authors.lastname: Bedogni
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism; D001132:Arm / Q000033:anatomy & histology / Q000502:physiology; D001823:Body Composition / Q000502:physiology*; D002138:Calibration; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D017097:Electric Impedance; D005260:Female; D006801:Humans; D007676:Kidney Failure, Chronic / Q000378:metabolism*; D007866:Leg / Q000033:anatomy & histology / Q000502:physiology; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000378:metabolism; D010530:Peritoneal Dialysis; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity