title: A single sample method for estimating glomerular filtration rate in cats.
abstract: BACKGROUND
  Validated methods of estimating glomerular filtration rate (GFR) in cats requiring only a limited number of samples are desirable.
  
  
  OBJECTIVE
  To test a single sample method of determining GFR in cats.
  
  
  METHODS
  The validation population (group 1) consisted of 89 client-owned cats (73 nonazotemic and 16 azotemic). A separate population of 18 healthy nonazotemic cats (group 2) was used to test the methods.
  
  
  METHODS
  Glomerular filtration rate was determined in group 1 using corrected slope-intercept iohexol clearance. Single sample clearance was determined using the Jacobsson and modified Jacobsson methods and validated against slope-intercept clearance. Extracellular fluid volume (ECFV) was determined from slope-intercept clearance with correction for the 1 compartment assumption and by deriving a prediction formula for ECFV (ECFV Predicted ) based on the body weight. The optimal single sample method was tested in group 2.
  
  
  RESULTS
  A blood sample at 180 minutes and ECFV Predicted were optimal for single sample clearance. Mean ± SD GFR in group 1 determined using the Jacobsson and modified Jacobsson formulae was 1.78 ± 0.70 and 1.65 ± 0.60 mL/min/kg, respectively. When tested in group 2, the Jacobsson method overestimated multisample clearance. The modified Jacobsson method (mean ± SD 2.22 ± 0.34 mL/min/kg) was in agreement with multisample clearance (mean ± SD 2.19 ± 0.34 mL/min/kg).
  
  
  CONCLUSIONS
  The modified Jacobsson method provides accurate estimation of iohexol clearance in cats, from a single sample collected at 180 minutes postinjection and using a formula based on the body weight to predict ECFV. Further validation of the formula in patients with very high or very low GFR is required.
authors: Royal Veterinary College, London, UK. natalie.finch@bristol.ac.uk
authors: N C
authors: NC
authors: Finch
authors: R
authors: R
authors: Heiene
authors: J
authors: J
authors: Elliott
authors: H M
authors: HM
authors: Syme
authors: A M
authors: AM
authors: Peters
mesh_terms: D000818:Animals; D053099:Azotemia / Q000097:blood / Q000175:diagnosis / Q000662:veterinary*; D002371:Cat Diseases / Q000175:diagnosis*; D002415:Cats; D003287:Contrast Media / Q000493:pharmacokinetics*; D005260:Female; D005919:Glomerular Filtration Rate / Q000662:veterinary*; D007472:Iohexol / Q000493:pharmacokinetics*; D008297:Male
chemical_list: D003287:Contrast Media; D007472:Iohexol
keywords: Clearance; Function; Iohexol; Renal