Evaluation of cystatin C as an endogenous marker of glomerular filtration rate in dogs

Frederic S. Almy, Mary M Christopher, Don P. King, Scott A. Brown

Research output: Contribution to journalArticlepeer-review

75 Scopus citations


Cystatin C is a cysteine protease inhibitor produced by all nucleated cells. It is freely filtered by the glomcrulus and is unaffected by nonrenal factors such as inflammation and gender. Because of greater sensitivity and specificity, cystatin C has been proposed to replace creatinine as a marker of glomerular filtration rate (GFR) in humans. The aims of this study were to validate an automated assay in canine plasma and to evaluate the usefulness of cystatin C as a marker of GFR in dogs. Western blotting was used to demonstrate cross-reactivity of an anti-human cystatin C antibody. An immunoturbidimetric assay was used to detect cystatin C in 25 clinically healthy dogs and 25 dogs with renal failure. Mean cystatin C concentration in the healthy dogs and the dogs with renal failure was 1.08 ± 0.16 mg/L and 4.37 ± 1.79 mg/L, respectively. Intra- and interassay variability was <5%. The assay was linear (r = .974) between 0.14 and 7.53 mg/L. Both cystatin C and creatinine concentrations were measured in banked, frozen serum from 20 remnant kidney model dogs and 10 volume-depleted dogs for which GFR measurements by exogenous creatinine clearance had been determined previously. In the remnant kidney model, cystatin C was better correlated with GFR than creatinine (r = .79 versus .54) but was less well correlated with GFR in volume-depleted dogs (r = .54 versus .95). GFR measurements were repeated in the remnant kidney model dogs 60 days after initial GFR measurements. At this time, cystatin C and creatinine concentrations correlated equally well with GFR (r = .891 versus .894, respectively). Cystatin C concentration is a reasonable alternative to creatinine for screening dogs with decreased GFR due to chronic renal failure.

Original languageEnglish (US)
Pages (from-to)45-51
Number of pages7
JournalJournal of Veterinary Internal Medicine
Issue number1
StatePublished - Jan 2002


  • Canine
  • Chronic renal failure
  • Creatinine
  • Creatinine clearance
  • Remnant kidney model
  • Test validation

ASJC Scopus subject areas

  • veterinary(all)


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