title: Serum cystatin C as a marker of the renal function.
abstract: The protease inhibitor cystatin C is a non-glycosylated low molecular weight protein (Mr=13359) which is produced by all nucleated cells at a constant rate, freely filtered by the renal glomeruli, and catabolized in the tubuli. The aim of the study was to elucidate the applicability of serum cystatin C as a marker of glomerular filtration rate (GFR) in patients with various kidney diseases with a wide range of renal function and in dialysis patients. Seventy-six patients with various kidney diseases (aged 20 to 79 years) and 61 dialysis patients (aged 21 to 82 years) were included. Serum cystatin C was measured by automated particle-enhanced immunoturbidimetry, serum and urine creatinine by an enzymatic method, and GFR by 99mTc-DTPA-clearance using a single plasma sample method. Serum cystatin C in patients with various kidney diseases was 1.90+/-0.98 mg/L (mean+/-SD) and in dialysis patients 7.14+/-1.91 mg/L. In the non-dialysis patients a linear relationship was found between 99mTc-DTPA-clearance and 1/serum cystatin C (r=0.91, p-value<0.0001), 1/serum creatinine (r=0.89, p-value<0.0001), and creatinine-clearance (r=0.88, p-value<0.0001). Comparison of the non-parametric ROC plots for serum cystatin C (area under the curve (AUC)=0.9665; SE=0.0169), serum creatinine (AUC=0.9554; SE=0.0205), and creatinine-clearance (AUC=0.9731; SE=0.0160) revealed no significant differences (p-values: 0.50, 0.78, and 0.49). In conclusion, cystatin C may be a likewise good marker of the GFR as serum creatinine and creatinine-clearance, cystatin C having the advantage being independent of gender and muscle mass.
authors.affiliation: Department of Internal Medicine, Viborg County Hospital, Denmark. elseranders@909mail.dk
authors.forename: E
authors.initials: E
authors.lastname: Randers
authors.forename: J H
authors.initials: JH
authors.lastname: Kristensen
authors.forename: E J
authors.initials: EJ
authors.lastname: Erlandsen
authors.forename: H
authors.initials: H
authors.lastname: Danielsen
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D003404:Creatinine / Q000097:blood; D055316:Cystatin C; D015891:Cystatins / Q000097:blood*; D015853:Cysteine Proteinase Inhibitors / Q000097:blood*; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007668:Kidney / Q000502:physiology*; D007674:Kidney Diseases / Q000097:blood / Q000503:physiopathology; D007677:Kidney Function Tests / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010531:Peritoneal Dialysis, Continuous Ambulatory; D019275:Radiopharmaceuticals; D006435:Renal Dialysis; D016284:Technetium Tc 99m Pentetate
chemical_list: D015415:Biomarkers; C525030:CST3 protein, human; D055316:Cystatin C; D015891:Cystatins; D015853:Cysteine Proteinase Inhibitors; D019275:Radiopharmaceuticals; D003404:Creatinine; D016284:Technetium Tc 99m Pentetate