P1088BRAND NEW METHOD TO CALCULATE THE VOLUME OF EXTRA CELLULAR FLUID IN HEMODIALYSIS PATIENT ONLY FROM REGULAR BLOOD TEST

Uric acid is a small molecule with molecular weight 168, but has an electrical pole which enables pass through the phospholipid bilayers of cell membranes by simple diffusion. Urate transport proteins of cell membranes (URAT1, GLUT9, OAT, MRP4, MCT9, NPT4, ABCG2) are expressed only in uric acid-excreting tissues. These findings suggest that uric acid does not pass through the cell membrane, either by diffusion or active transport. Since uric acid does not pass through cell membranes, the uric acid distribution volume (UDiV) would reflect the extracellular volume (ECV). At ASN 2018, we reported that UDiV significantly correlated with ECV predicted by the bio-impedance method measured by InBody, S 20 (Biospace Co., Ltd, Korea). However, both data were correlated, there was a large fixed error. This time, we examined the correlation with the UDiV again using the Fresenius BCM (Fresenius Medical Care, Bad Homberg, Germany), which is trusted worldwide. We calculated UDiV from regular blood test results by uric acid kinetic modeling. This study was performed in Yokohama Minami Clinic. One hundred nine patient under hemodialysis was consented and enrolled in this study. The HD patients were 59males and 50females. 68.0±10.9years old. We performed UDiV calculation from blood samples obtained before and after hemodialysis. Then, after the hemodialysis session, 30minutes interval was made to measure the BIA-ECV using BCM. Then, we compared UDiV with BIA-ECV . We used least squares regression analysis and Bland–Altman analysis to compare the UDiV method and the BIA-ECV method, and the Steel test for multiple comparisons of UDiV and symptoms. All analyses were performed using JMP 9.0.2 (SAS Institute, Inc., Cary, NC, USA). There was a significant correlation between UDiV(x) and BIA-ECFV (y): (y = 0.70x +3.02, r-square = 0.61, p < 0.0001, Figure 1a). The regression line closely coincided with the line of identity. Bland–Altman analysis showed a systematic error for UDiVvs. BIA-ECV (Figure 1b). There was a significant difference between UDiVand BIA-ECV (mean difference 1.32 L, 95% CI -2.6 to 5.2 L). UdiV could be a viable alternative marker of BIA-ECV for the assessment of hydration status of patients with HD.