title: Estimation of body composition and normal fluid status using a calf bioimpedance technique.
abstract: The aims of this study in hemodialysis (HD) patients were: 1. To evaluate the relationship of calf bioimpedance with total body composition and fluid status as measured by gold standard methods. 2. To investigate the ability of calf normalized resistivity (CNR) to predict the normal fluid status (dry weight: DW) in a prospective study. In the body composition study (n = 41), fluid status (ECV(Br)/FFM(MRI)), muscle mass (MM(MRI)), and total adipose tissue (TAT(MRI)) were measured by dilution (D2O and Br) and MRI methods three hours prior to HD treatment. Calf extracellular and intracellular resistance, resistivity, and CNR were measured with a multi-frequency bioimpedance device (Hydra 4200). In the fluid status study (n = 32 with 429 measurements), a nonlinear model based on the differences in CNR between patients and healthy subjects was established to predict DW(cBIS) previously determined by a separate continuous calf bioimpedance spectroscopy (cBIS) method. CNR significantly correlated with a gold standard hydration marker (ECV(Br)/FFM(MRI)). Calf body composition models were highly correlated with MM(MRI) (R(2) = 0.85) and TAT(MRI) (R(2) = 0.85). DW(cBIS) prediction was validated with a CNR model in the degree of differences of 0.94 ± 0.18, 0.39 ± 0.7 and -0.02 ± 0.8 kg from DW(cBIS) when post HD fluid overload was 1.8 ± 1.2, 1.15 ± 0.8 and 0.54 ± 0.5 kg, respectively. These differences are not considered to be clinically significant.
  
  
  CONCLUSIONS
  This practical method of calf bioimpedance is useful to predict body composition and normal fluid status in dialysis patients.
authors: Renal Research Institute, New York, N.Y., USA.
authors: Fansan
authors: F
authors: Zhu
authors: Nathan W
authors: NW
authors: Levin
mesh_terms: D000273:Adipose Tissue / Q000503:physiopathology; D000328:Adult; D000368:Aged; D001823:Body Composition; D001826:Body Fluids; D001835:Body Weight; D017097:Electric Impedance; D005260:Female; D006801:Humans; D007676:Kidney Failure, Chronic / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000295:instrumentation*; D018482:Muscle, Skeletal / Q000503:physiopathology; D011446:Prospective Studies; D012044:Regression Analysis; D006435:Renal Dialysis