title: Diagnostic value of plasma cystatin C as a glomerular filtration marker in decompensated liver cirrhosis.
abstract: BACKGROUND
  Plasma creatinine concentration and calculated creatinine clearance are of limited value as glomerular filtration rate (GFR) markers in patients with decompensated liver cirrhosis. We assessed plasma cystatin C as an indicator of GFR in such patients.
  
  
  METHODS
  We studied 36 patients with decompensated liver cirrhosis and 56 noncirrhotic controls, both groups including individuals with normal and impaired renal function. GFR was measured in all individuals by inulin clearance, with values <72 mL x min(-1) x 1.73 m(-2) considered decreased. We measured cystatin C and creatinine in plasma and calculated (from plasma concentrations) and measured creatinine clearances, using for them decision points of 1.25 mg/L, 115 micromol/L, and 72 and 72 mL x min(-1) x 1.73 m(-2), respectively.
  
  
  RESULTS
  Plasma cystatin C concentrations were similar in controls and cirrhotics and, at the usual cutpoint, could detect decreased GFR with similar sensitivities in the two groups (73% and 88%, respectively). Serum creatinine was markedly lower in cirrhotics and remained mostly within the reference interval at all GFR values; the diagnostic sensitivity of creatinine was much lower in cirrhotics than in controls (23% vs 64%). Lower diagnostic sensitivity was also observed for calculated creatinine clearance (53% vs 100% in controls), whereas similar sensitivities were found for measured creatinine clearance (86% and 81%) in controls and cirrhotics, respectively. ROC analysis showed that all four variables had similar diagnostic accuracies in cirrhotic patients. However, it also revealed that good diagnostic accuracies for plasma creatinine and calculated creatinine clearance can be obtained only if reference intervals different from those used for the general population are adopted.
  
  
  CONCLUSIONS
  Plasma cystatin C concentration is an accurate GFR marker in cirrhotic patients. Plasma creatinine concentration and calculated creatinine clearance are of no practical value, as their reference values vary with the severity of the liver disease.
authors.affiliation: Department of Medical and Surgical Sciences, University of Padua, Largo E. Meneghetti 2, 35131 Padua, Italy.
authors.forename: Rocco
authors.initials: R
authors.lastname: Orlando
authors.forename: Michele
authors.initials: M
authors.lastname: Mussap
authors.forename: Mario
authors.initials: M
authors.lastname: Plebani
authors.forename: Pierpaolo
authors.initials: P
authors.lastname: Piccoli
authors.forename: Sara
authors.initials: S
authors.lastname: De Martin
authors.forename: Maura
authors.initials: M
authors.lastname: Floreani
authors.forename: Roberto
authors.initials: R
authors.lastname: Padrini
authors.forename: Pietro
authors.initials: P
authors.lastname: Palatini
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D003430:Cross-Sectional Studies; D055316:Cystatin C; D015891:Cystatins / Q000097:blood*; D005919:Glomerular Filtration Rate; D006801:Humans; D007118:Immunoassay; D008103:Liver Cirrhosis / Q000097:blood / Q000175:diagnosis* / Q000652:urine; D008297:Male; D008875:Middle Aged; D009391:Nephelometry and Turbidimetry
chemical_list: D015415:Biomarkers; C525030:CST3 protein, human; D055316:Cystatin C; D015891:Cystatins