Felis ISSN 2398-2950

Blood biochemistry: urea

Synonym(s): Blood urea nitrogen, BUN

Contributor(s): Kathleen P Freeman

Overview

  • Produced in liver from ammonia derived from tissue/dietary protein and excreted by kidneys.
  • Important marker of kidney function Kidney: chronic kidney disease, protein metabolism and upper gastrointestinal tract hemorrhage.

Sampling

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Tests

Methodologies

  • Typically measured as (total) blood urea nitrogen (BUN). (Based on nitrogen portion of urea.)
  • Blood urea is based on the entire molecule of urea.
  • Blood strips can be used to get rapid results. Do not give precise reading but will show if levels are significantly elevated.

Availability

  • Widely available.

Validity

Sensitivity

  • Low sensitivity in detection of renal dysfunction. Renal mass must be reduced by approximately 75% before BUN values are consistently outside of reference interval.

Specificity

  • Low specificity for detection of renal dysfunction.

Technique (intrinsic) limitations

  • Only significant in conjunction with other laboratory and clinical findings.
    Most useful to assess in conjunction with a urine specific gravity Urinalysis: specific gravity.

Result Data

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Further Reading

Publications

Refereed papers

Other sources of information

  • 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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