title: Evaluation of Cystatin C for the Detection of Chronic Kidney Disease in Cats.
abstract: BACKGROUND
  Serum cystatin C (sCysC) and urinary cystatin C (uCysC) are potential biomarkers for early detection of chronic kidney disease (CKD) in cats. An in-depth clinical validation is required.
  
  
  OBJECTIVE
  To evaluate CysC as a marker for CKD in cats and to compare assay performance of the turbidimetric assay (PETIA) with the previously validated nephelometric assay (PENIA).
  
  
  METHODS
  Ninety cats were included: 49 CKD and 41 healthy cats.
  
  
  METHODS
  Serum CysC and uCysC concentrations were prospectively evaluated in cats with CKD and healthy cats. Based on plasma exo-iohexol clearance test (PexICT), sCysC was evaluated to distinguish normal, borderline, and low GFR. Sensitivity and specificity to detect PexICT < 1.7 mL/min/kg were calculated. Serum CysC results of PENIA and PETIA were correlated with GFR. Statistical analysis was performed using general linear modeling.
  
  
  RESULTS
  Cats with CKD had significantly higher mean ± SD sCysC (1.4 ± 0.5 mg/L) (P < .001) and uCysC/urinary creatinine (uCr) (291 ± 411 mg/mol) (P < .001) compared to healthy cats (sCysC 1.0 ± 0.3 and uCysC/uCr 0.32 ± 0.97). UCysC was detected in 35/49 CKD cats. R(2) values between GFR and sCysC or sCr were 0.39 and 0.71, respectively (sCysC or sCr = μ + GFR + ε). Sensitivity and specificity were 22 and 100% for sCysC and 83 and 93% for sCr. Serum CysC could not distinguish healthy from CKD cats, nor normal from borderline or low GFR, in contrast with sCr.
  
  
  CONCLUSIONS
  Serum CysC is not a reliable marker of reduced GFR in cats and uCysC could not be detected in all CKD cats.
authors.affiliation: Department of Medicine and Clinical Biology of Small Animals, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.
authors.forename: L F E
authors.initials: LF
authors.lastname: Ghys
authors.affiliation: Department of Medicine and Clinical Biology of Small Animals, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.
authors.forename: D
authors.initials: D
authors.lastname: Paepe
authors.affiliation: Clinical Research Unit, National Veterinary School of Toulouse, Toulouse Cedex 3, France.
authors.forename: H P
authors.initials: HP
authors.lastname: Lefebvre
authors.affiliation: Clinical Research Unit, National Veterinary School of Toulouse, Toulouse Cedex 3, France.
authors.forename: B S
authors.initials: BS
authors.lastname: Reynolds
authors.affiliation: Department of Pharmacology, Toxicology and Biochemistry, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.
authors.forename: S
authors.initials: S
authors.lastname: Croubels
authors.affiliation: Department of Pharmacology, Toxicology and Biochemistry, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.
authors.forename: E
authors.initials: E
authors.lastname: Meyer
authors.affiliation: Department of Clinical Chemistry, Microbiology and Immunology, Faculty of Health Medicine and Life Sciences, Ghent University, Gent, Belgium.
authors.forename: J R
authors.identifier: http://orcid.org/0000-0002-5702-6792
authors.initials: JR
authors.lastname: Delanghe
authors.affiliation: Department of Medicine and Clinical Biology of Small Animals, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.
authors.forename: S
authors.initials: S
authors.lastname: Daminet
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000097:blood* / Q000652:urine; D016022:Case-Control Studies; D002371:Cat Diseases / Q000097:blood / Q000175:diagnosis* / Q000652:urine; D002415:Cats; D055316:Cystatin C / Q000097:blood* / Q000652:urine; D005260:Female; D008297:Male; D009391:Nephelometry and Turbidimetry / Q000662:veterinary; D011237:Predictive Value of Tests; D012016:Reference Values; D051436:Renal Insufficiency, Chronic / Q000662:veterinary*
chemical_list: D015415:Biomarkers; D055316:Cystatin C
keywords: Chronic kidney disease; Creatinine; Feline; Glomerular Filtration Rate