Table 4. The trend of the relationship between residual renal function and biochemical parameters.

Variables	residual GFR (median)a				P
	Q1(0–25%)	Q2(25%-50%)	Q3(50%-75%)	Q4(75%-100%)
nPCR	0.70	0.57	2.37	2.24	<0.001
P3-	2.46	1.97	0.91	0.57	<0.001
Cl-	0.48	1.39	1.70	3.66	<0.001
Mg2+	2.06	1.92	1.23	0.49	0.025
creatinine	2.78	1.74	1.07	0.48	<0.001
24h urine volume	0.00	0.77	2.30	3.35	<0.001

^a the median of residual GFR among groups classified by the interquartile range of biochemical parameters.