title: Comparison of serum concentrations of symmetric dimethylarginine and creatinine as kidney function biomarkers in cats with chronic kidney disease.
abstract: BACKGROUND
  Symmetric dimethylarginine (SDMA) has been shown to be an accurate and precise biomarker for calculating estimated glomerular filtration rate (GFR) in humans, as well as a more sensitive biomarker than serum creatinine concentration (sCr) for assessing renal dysfunction.
  
  
  OBJECTIVE
  The purpose of this retrospective study was to report on the utility of measuring serum SDMA concentrations in cats for detection of chronic kidney disease (CKD) before diagnosis by conventional measurement of sCr.
  
  
  METHODS
  Chronic kidney disease cats (n = 21) included those persistently azotemic for ≥3 months (n = 15), nonazotemic cats with GFR >30% decreased from median GFR of normal cats (n = 4), and nonazotemic cats with calcium oxalate kidney stones (n = 2). Healthy geriatric cats (n = 21) were selected from the same colony.
  
  
  METHODS
  Symmetric dimethylarginine concentrations (liquid chromatography-mass spectroscopy) and sCr (enzymatic colorimetry) were determined retrospectively from historical data or banked serum samples in azotemic cats or at the time GFR (iohexol clearance) was measured in nonazotemic cats.
  
  
  RESULTS
  Serum SDMA (r = -0.79) and sCr (r = -0.77) concentrations were significantly correlated to GFR (both P < .0001). Symmetric dimethylarginine became increased before sCr in 17/21 cats (mean, 17.0 months; range, 1.5-48 months). Serum SDMA had higher sensitivity (100%) compared with sCr (17%), but lower specificity (91% versus 100%) and positive predictive value (86% versus 100%).
  
  
  CONCLUSIONS
  Using serum SDMA as a biomarker for CKD allows earlier detection of CKD in cats compared with sCr, which may be desirable for initiating renoprotective interventions that slow progression of CKD.
authors.affiliation: Department of Biomedical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR.
authors.forename: J A
authors.initials: JA
authors.lastname: Hall
authors.forename: M
authors.initials: M
authors.lastname: Yerramilli
authors.forename: E
authors.initials: E
authors.lastname: Obare
authors.forename: M
authors.initials: M
authors.lastname: Yerramilli
authors.forename: D E
authors.initials: DE
authors.lastname: Jewell
mesh_terms: D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives* / Q000097:blood; D015415:Biomarkers / Q000097:blood; D002371:Cat Diseases / Q000097:blood* / Q000175:diagnosis; D002415:Cats; D003404:Creatinine / Q000097:blood*; D005260:Female; D005919:Glomerular Filtration Rate / Q000662:veterinary; D008297:Male; D051436:Renal Insufficiency, Chronic / Q000097:blood / Q000175:diagnosis / Q000662:veterinary*; D012189:Retrospective Studies
chemical_list: D015415:Biomarkers; C024917:symmetric dimethylarginine; D001120:Arginine; D003404:Creatinine
keywords: Endogenous; Feline; Pet foods; Predictor