Kidney Week

Abstract: SA-PO868

A New Method to Estimate the Extra-Cellular Fluid Volume with Serum Uric Acid Concentrations at Pre- and Post-Hemodialysis

Session Information

• Dialysis: Cardiovascular, BP, Volume
  October 27, 2018 | Location: Exhibit Hall, San Diego Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Dialysis

• 701 Dialysis: Hemodialysis and Frequent Dialysis

Authors

• Ito, Takahito, Kataguilli Medical Center, Shibata, Japan

Takahito Ito,

• Shinzato, Takahiro, Daiko Medical Engineering Research Institute, Nagoya-shi,, Japan

Takahiro Shinzato,

• Shibata, Kazuhiko, Yokohama Minami Clinic, Yokohama, Japan

Kazuhiko Shibata,

• Nakai, Shigeru, Fujita Health University School of Health Scieneces, Toyoake, Aichi, Japan

Shigeru Nakai,

• Aoki, Takeshi, Nagoya Municipal Industrial Research Institute, Iwakura-shi, Aichi-ken, Japan

Takeshi Aoki,

Background

Uric acid (UA) with a molecular weight of 168 Da is synthesized mainly in the liver and intestines as the end-product of purine metabolism, and is located throughout the body. We have found that we could approximate the extra-cellular fluid volume (ECV) with the amount of UA that was removed by hemodialysis (HD).

Methods

Our calculation is based on assumptions shown in the figure. The dialyzer mass transfer-area coefficient (KoA) and the physiologically-appropriate patient clearance time (tp) for UA were obtained in advance. In order to estimate ECV after HD (ECVa), clinical parameters required other than C_UA at pre- and post-HD were height, treatment time of HD, blood flow rate of HD, dialysate flow rate of HD, surface area of dialysis membranes, hematocrit at pre-HD, body weight values at pre- and post-HD, C_UN at pre- and post-HD, and C_Na at pre- and post-HD. The ECAa values estimated by our method were compared with those which were measured by multi-frequency bioimpedance analysis (BIA).

Results

We named our new method UA-assisted ECV Estimation (U-EVE) and assembled it as a Microsoft EXCEL® file for practice. ECVa values by U-EVE correlated with those by BIA: R=0.456 (P=0.0100, N=31, age 62.3±11.4, BIA was done by MLT555N), R=0.578 (P=0.0190, N=16, age 65.5±9.3, by InBody S10), and R=0.616 (P<0.0001, N=49, age 59.6±11.3, by MLT50) in three independent measurements. The formulas used in our program will be explained step by step.

Conclusion

U-EVE is innovative yet easy to estimate ECVa of HD patients without special devices. Clinical significances of U-EVE need to be further verified.

Major assumptions about our method. (1) Removed UA molecules come only from ECS, (2) UA and Na⁺ do not cross cell membrane during HD, (3) Water crosses cell membrane to maintain the ratio of C_Na⁺ of ECS to that of ICS, (4) C_UA of ECS rebounds after HD simply due to redistribution of UA from hypo-perfused space of ECS (arrowhead). ECS and ICS stand for extra-cellular and intra-cellular spaces, respectively. Black dots represent UA molecules.

Funding

• Clinical Revenue Support