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

• Hemodialysis and Frequent Dialysis - I
  November 07, 2019 | Location: Exhibit Hall, Walter E. Washington Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Dialysis

• 701 Dialysis: Hemodialysis and Frequent Dialysis

Authors

• Hanafusa, Norio, Tokyo Women's Medical University, Shinjuku-ku, TOKYO, Japan

Norio Hanafusa,

• Suzuki, Shunji, Tokyo Woman Medical University, Tokyo, Japan

Shunji Suzuki,

• Akiyama, Kenichi, Tokyo Women's Medical University, Shinjuku-ku, TOKYO, Japan

Kenichi Akiyama,

• Kamei, Daigo, Tokyo Women's Medical University, Shinjuku-ku, TOKYO, Japan

Daigo Kamei,

• Tanaka, Nobue, Tokyo Women's Medical University, Shinjuku-ku, TOKYO, Japan

Nobue Tanaka,

• Tsukada, Misao, Kidney Center,Tokyo Women's Medical University, Tokyo, Japan

Misao Tsukada,

• Nitta, Kosaku, Tokyo Women's Medical University, Shinjuku-ku, TOKYO, Japan

Kosaku Nitta,

• Tsuchiya, Ken, Tokyo Women's Medical University, Shinjuku-ku, TOKYO, Japan

Ken Tsuchiya,

Background

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 (V_UA/V_UN) can be a surrogate marker of ECW/TBW measured by BIA.

Methods

In total, 108 patients who were receiving HD at our facility and who underwent BIA in 2018 were included in this study. V_UA/V_UN 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.

Results

V_UA/V_UN and ECW/TBW were 0.646 ± 0.062 and 0.393 ± 0.014, respectively. ECW/TBW was highly correlated with V_UA/V_UN (ECW/TBW = 0.274 + 0.184* V_UA/V_UN). Multivariate analysis demonstrated that only creatinine and ECW/TBW were significantly associated with the regression residuals. The cut-off values of V_UA/V_UN 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.

Conclusion

V_UA/V_UN 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 V_UA/V_UN, so this measure is widely applicable, even in epidemiological studies, without the need for dedicated devices.