Table 3.

Correlation of PBUTs and commonly used filtration markers with tubular markers.

Markers	Plasma NGAL		uNGAL/uCr		uCysC/uCr
	6 months	8 months	6 months	8 months	6 months	8 months
Plasma indoxyl sulfate	0.50**	0.44**	0.50*	0.36*	0.54**	0.32
Plasma hippuric acid	0.54**	0.65***	0.63**	0.66***	0.74***	0.45*
Plasma kynurenic acid	0.23	0.58***	0.43*	0.48**	0.53*	0.40*
Indoxyl sulfate surrogate clearance	− 0.45*	− 0.09	− 0.64**	− 0.12	− 0.45*	− 0.28
Hippuric acid surrogate clearance	− 0.58**	− 0.30	− 0.68***	− 0.23	− 0.71***	− 0.14
Kynurenic acid surrogate clearance	− 0.40*	− 0.50**	− 0.44*	− 0.56**	− 0.47*	− 0.36*
Indoxyl sulfate fractional excretion	− 0.57**	0.06	− 0.48*	0.09	− 0.38	− 0.14
Hippuric acid fractional excretion	− 0.48*	− 0.13	− 0.58**	0.02	− 0.59**	− 0.00
Kynurenic acid fractional excretion	− 0.39	− 0.40*	− 0.36	− 0.41*	− 0.41	− 0.23
Plasma creatinine	0.23	− 0.05	0.31	0.24	0.05	0.17
Creatinine clearance	0.31	− 0.11	0.17	0.45*	0.40	0.10
Plasma Cystatin C	0.33	− 0.11	0.41	− 0.14	0.05	− 0.14
Albuminuria	0.39	− 0.05	0.27	0.51**	0.36	0.52**

Non-parametric Spearman correlation was performed, and the data are presented as Spearman rank, where ‘-’ indicates negative correlation. ***P < 0.001, **P < 0.01, *P < 0.05. PBUTs: protein-bound uremic toxins; cl: clearance; NGAL: neutrophil gelatinase-associated lipocalin; Cr: creatinine; Cys C: cystatin C; uCr: Urinary creatinine.

Significant values are in [bold].