Table 3. P-values of comparison between concentrations for characteristics as divided in quartiles or dichotomically.

	Age	BW	Kt/V	PNA	RRF	vintage	gender	DM
urea	0.097	0.116	0.478	<0.001	0.265	0.219	0.310	0.728
Crea	0.129	0.015	0.339	0.027	0.345	0.441	0.004	0.842
ADMA	0.616	0.458	0.396	0.848	0.337	0.683	0.492	0.814
SDMA	0.408	0.891	0.297	0.548	0.196	0.794	0.797	0.668
UA	0.002	0.026	0.097	0.004	0.240	0.026	0.025	0.171
β2M	0.898	0.666	0.585	0.607	<0.001	0.644	0.346	0.916
HA	0.539	0.577	0.602	0.036	0.004	0.268	0.247	0.378
IS	0.850	0.462	0.340	0.261	0.159	0.664	0.839	0.259
IAA	0.678	0.251	0.583	0.203	0.089	0.959	0.437	0.402
PCS	0.283	0.698	0.809	0.001	0.815	0.739	0.452	0.312
PCG	0.230	0.786	0.391	0.067	0.041	0.766	0.273	0.291
CMPF	0.065	0.537	0.316	0.464	0.073	0.984	0.865	0.106
Free HA	0.491	0.580	0.629	0.092	0.002	0.181	0.277	0.384
Free IS	0.505	0.605	0.620	0.266	0.006	0.772	0.976	0.110
Free IAA	0.633	0.219	0.480	0.660	0.002	0.978	0.440	0.107
Free PCS	0.263	0.604	0.858	0.007	0.050	0.601	0.445	0.036
Free PCG	0.205	0.763	0.409	0.070	0.038	0.777	0.300	0.317

Crea: creatinine, ADMA: asymmetric dimethylarginine, SDMA: symmetric dimethylarginine, UA: uric acid, β₂M: beta-2-microglobulin, HA: hippuric acid, IS: indoxyl sulfate, IAA: indole acetic acid, PCS: p-cresylsulfate, PCG: p-cresylglucuronide, CMPF: 3-carboxy-4-methyl-5-propyl-2-furanpropionic acid.

BW: body weight, PNA: protein equivalent of nitrogen appearance, RRF: residual renal function, DM: diabetes mellitus.

P<0.05 is indicated in bold.