Felis ISSN 2398-2950

Blood biochemistry: creatinine

Synonym(s): Serum creatinine

Contributor(s): Kathleen P Freeman, Ludovic Pelligand

Overview

  • Derived from breakdown of creatinine in muscle.
  • Excreted by kidneys.
  • Not influenced by protein metabolism (unlike urea Blood biochemistry: urea).
  • Important marker of renal function Kidney: chronic kidney disease; levels controlled by excretion rate.
  • Plasma concentration also depends on muscle mass.

Sampling

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Tests

Methodologies

  • Colorimetric method: reaction between alkaline picrate solution and creatinine. Non-creatinine chromagens and other compounds may also react with alkaline picrate solution.
  • Enzymatic method: no artifacts caused by chromagens.

Availability

  • Widely available.

Validity

Sensitivity

  • Better indicator of glomerular filtration rate (GFR) than BUN, but increases in serum creatinine are not in proportion to the decrease in GFR.
  • Low sensitivity for detection of renal disease (especially if poor body condition and muscle mass).
  • Must be used in conjunction with other tests especially urine specific gravity.

Specificity

  • Varies along the day with food intake.
  • Must be used in conjunction with other tests (especially urine specific gravity).

Technique (intrinsic) limitations

  • Interpret in conjunction with other laboratory and clinical findings.

Result Data

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Further Reading

Publications

Refereed papers

Other sources of information

  • International Renal Interest Society, IRIS Staging of CKD: http://www.iris-kidney.com.
  • Ettinger S J & Feldman E C (eds) (2000) Textbook of Veterinary Internal Medicine. 5th edn. Philadelphia: W B Saunders & Co.
  • Kaneko J J, Harvey J W & Brass M L (eds) (1997) Clinical Biochemistry of Domestic Animals. 5th edn. Boston: Academic Press.
  • Duncan J R, Prasse K W & Mahaffey E A (1994) Veterinary Laboratory Medicine. Clinical Pathology. 3rd edn. Iowa: Iowa University Press.


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