title: Body composition in renal transplant patients: bioimpedance analysis compared to isotope dilution, dual energy X-ray absorptiometry, and anthropometry.
abstract: Whether multifrequency bioelectrical impedance analysis (MF-BIA), a relatively new method for measuring body composition, is also applicable for accurate body composition measurements in renal transplant (RTx) patients is not known. Therefore, the use of MF-BIA is validated in 77 RTx patients with a stable renal function at least 2 yr posttransplantation. MF-BIA is compared to isotope dilution techniques for measurement of body water compartments, and to dual energy x-ray absorptiometry (DEXA) and anthropometry for measurement of fat and fat free mass. Finally, DEXA and anthropometry are compared to each other. Method agreement is assessed by intraclass correlation coefficients (ICC) and plotted by Bland and Altman analysis. MF-BIA significantly underestimates total body water (TBW, 0.7+/-2.1 L) and overestimates the extracellular water (ECW, 3.3+/-1.8 L) compared to isotope dilution; the ICC between both techniques is 0.943 for TBW and 0.846 for ECW. The percentage body fat (BF) measured by MF-BIA is significantly higher than both BF measured by DEXA (3.4+/-4.7%) or by anthropometry (5.5+/-5.2%). The ICC between MF-BIA and DEXA is 0.887 and between MF-BIA and anthropometry 0.856. BF measured by DEXA is significantly higher than BF measured by anthropometry (2.1+/-4.4%); their ICC is 0.913. In conclusion, MF-BIA seems to be suitable for measurement of TBW in RTx patients; however, method agreement between isotope dilution and MF-BIA for the measurement of ECW is not satisfactory. In the assessment of fat and fat free mass, the reliability of MF-BIA appears to be questionable. Method agreement between DEXA and anthropometry seems to be slightly better.
authors.affiliation: Department of Internal Medicine, University Hospital Maastricht, The Netherlands. E.vandenham@intmed.unimaas.nl
authors.forename: E C
authors.initials: EC
authors.lastname: van den Ham
authors.forename: J P
authors.initials: JP
authors.lastname: Kooman
authors.forename: M H
authors.initials: MH
authors.lastname: Christiaans
authors.forename: F H
authors.initials: FH
authors.lastname: Nieman
authors.forename: B K
authors.initials: BK
authors.lastname: Van Kreel
authors.forename: G A
authors.initials: GA
authors.lastname: Heidendal
authors.forename: J P
authors.initials: JP
authors.lastname: Van Hooff
mesh_terms: D015502:Absorptiometry, Photon; D000273:Adipose Tissue / Q000473:pathology; D000328:Adult; D000886:Anthropometry; D001823:Body Composition / Q000502:physiology*; D001834:Body Water / Q000378:metabolism; D017097:Electric Impedance; D005110:Extracellular Space / Q000378:metabolism; D005260:Female; D006801:Humans; D007201:Indicator Dilution Techniques; D016030:Kidney Transplantation; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period; D015203:Reproducibility of Results; D012885:Skinfold Thickness