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Kidney Week

Abstract: TH-PO227

Uric Acid Distribution Adjusted by Urea Distribution Volume Is a Promising Marker of Hydration Status in Hemodialysis Patients

Session Information

Category: Dialysis

  • 701 Dialysis: Hemodialysis and Frequent Dialysis


  • Hanafusa, Norio, Tokyo Women's Medical University, Shinjuku-ku, TOKYO, Japan
  • Suzuki, Shunji, Tokyo Woman Medical University, Tokyo, Japan
  • Akiyama, Kenichi, Tokyo Women's Medical University, Shinjuku-ku, TOKYO, Japan
  • Kamei, Daigo, Tokyo Women's Medical University, Shinjuku-ku, TOKYO, Japan
  • Tanaka, Nobue, Tokyo Women's Medical University, Shinjuku-ku, TOKYO, Japan
  • Tsukada, Misao, Kidney Center,Tokyo Women's Medical University, Tokyo, Japan
  • Nitta, Kosaku, Tokyo Women's Medical University, Shinjuku-ku, TOKYO, Japan
  • Tsuchiya, Ken, Tokyo Women's Medical University, Shinjuku-ku, TOKYO, Japan

Hemodialysis (HD) patients are prone to developing volume disturbance. Bioelectrical impedance analysis (BIA) provides indices for evaluating volume status, although this requires a dedicated machine, which precludes it from other general clinical use. Uric acid (UA) barely crosses the cell membrane, while urea does so readily. The volume of distribution (Vd) of UA and urea can be considered markers of extracellular water (ECW) and total body water (TBW), respectively. We investigated whether the ratio of the Vd of UA and urea (VUA/VUN) can be a surrogate marker of ECW/TBW measured by BIA.


In total, 108 patients who were receiving HD at our facility and who underwent BIA in 2018 were included in this study. VUA/VUN was calculated using the single-pool model. We compared ECW/TBW values after dialysis measured by BIA (InBody S10; InBody, Tokyo, Japan). We investigated factors associated with residuals from regression. We also evaluated the predictive ability of overhydration (ECW/TBW ≥ 0.4) or dehydration (ECW/TBW < 0.38) in two randomly selected groups, the training group and the validation group.


VUA/VUN and ECW/TBW were 0.646 ± 0.062 and 0.393 ± 0.014, respectively. ECW/TBW was highly correlated with VUA/VUN (ECW/TBW = 0.274 + 0.184* VUA/VUN). Multivariate analysis demonstrated that only creatinine and ECW/TBW were significantly associated with the regression residuals. The cut-off values of VUA/VUN for overhydration and dehydration were 0.666 and 0.579, respectively, in the training group. The corresponding area under the receiver operating characteristic curves were 0.872 and 0.898, respectively. The sensitivity and specificity values in the validation group were 0.571 and 0.868 for overhydration and 0.444 and 0.953 for dehydration, respectively.


VUA/VUN was not only associated with ECW/TBW but was also highly predictive of hydration status evaluated by BIA. We need only blood tests before and after the dialysis session for estimating VUA/VUN, so this measure is widely applicable, even in epidemiological studies, without the need for dedicated devices.