Fig. 1Strong correlations between the glomerular filtration rate (GFR) measurements based on the Modification of Diet in Renal Disease equation and those based on the new equation in the chronic kidney disease patients (A; r=0.79, P<0.0001) and the healthy individuals (B; r=0.36, P=0.01). It is commonly accepted that correlation coefficients (r values) between 0 and 0.2 indicate no correlations, those between 0.2 and 0.4 indicate weak low correlations, those between 0.4 and 0.6 indicate moderate correlations, and those above 0.8 indicate strong correlations.
Fig. 2Associations of serum creatinine and cystatin C with body weight, muscle mass, and age in the healthy individuals. (A) The correlation between serum creatinine and body weight (r=0.64, P<0.0001). (B) The correlation between serum creatinine and muscle mass (r=0.71, P<0.0001). (C) The correlation between serum creatinine and age (r=0.23, P=0.1462). (D) The correlation between serum cystatin C and body weight (r=0.48, P=0.0019). (E) The correlation between serum cystatin C and muscle mass (r=0.48, P=0.0021). (F) The correlation between serum cystatin C and age (r=0.16, P=0.3089).
Fig. 3Associations of serum creatinine and cystatin C with body weight, muscle mass and age in the diabetic chronic kidney disease patients. (A) The correlation serum creatinine and body weight (r=-0.05, P=0.7348). (B) The correlation between serum creatinine and height (r=-0.12, P=0.4708). (C) The correlation between serum creatinine and age (r=-0.003, P=0.9833). (D) The correlation between serum cystatin C and body weight (r=-0.29, P=0.0745). (E) The correlation between serum cystatin C and height (r=-0.24, P=0.1360). (F) The correlation between serum cystatin C and age (r=0.16, P=0.3384).
Table 1Demographic data for the 37 diabetic chronic kidney disease patients and the healthy individuals
Table 2Serum creatinine and serum cystatin C according to gender for the healthy population and the diabetic chronic kidney disease patients
Table 3Precision study of the cystatin C assay using low and high controls