Serum Cystatin C as an Endogenous Marker of Renal Function in Patients with Chronic Kidney Disease

Figures & data

Figure 1. Correlation between ⁵¹CrEDTA clearance (mL/min/1.73 m²) and reciprocal of serum creatinine (1/μmol/L) (r = 0.855; p < 0.0001).

Figure 2. Correlation between ⁵¹CrEDTA clearance (mL/min/1.73 m²) and reciprocal of serum cystatin C (1/mg/L) (r = 0.898; p < 0.0001).

Figure 3. Correlation between ⁵¹CrEDTA clearance (mL/min/1.73 m²) and creatinine clearance, calculated from Cockcroft and Gault formula (mL/min/1.73 m²) (r = 0.811; p < 0.0001).

Table 1 ROC curves comparisons for serum cystatin C, serum creatinine, and calculated creatinine clearance from Cockcroft-Gault formula

GFR cut-off level	Parameter	AUC	p
80 mL/min/1.73 m^2	Serum cystatin C	0.924	—
	Serum creatinine	0.900	0.352
	Creatinine clearance (C&G)	0.889	0.468
70 mL/min/1.73 m^2	Serum cystatin C	0.943	—
	Serum creatinine	0.906	0.032
	Creatinine clearance (C&G)	0.901	0.173
60 mL/min/1.73 m^2	Serum cystatin C	0.970	—
	Serum creatinine	0.944	0.042
	Creatinine clearance (C&G)	0.918	0.028
50 mL/min/1.73 m^2	Serum cystatin C	0.977	—
	Serum creatinine	0.945	0.009
	Creatinine clearance (C&G)	0.938	0.042
40 mL/min/1.73 m^2	Serum cystatin C	0.983	—
	Serum creatinine	0.962	0.008
	Creatinine clearance (C&G)	0.939	0.042
30 mL/min/1.73 m^2	Serum cystatin C	0.954	—
	Serum creatinine	0.953	0.927
	Creatinine clearance (C&G)	0.936	0.211

p values are given relative to the serum cystatin C.

*statistically significant.

Figure 4. ROC curve analysis of diagnostic accuracy of serum cystatin C, serum creatinine, and calculated clearance (from Cockcroft and Gault formula). The GFR determined with ⁵¹CrEDTA was used as the gold standard, and cut-off value was set at 50 mL/min/1.73 m².