Overview

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

Sampling

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 a 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

Further Reading

Publications

Refereed papers

• Recent references from VetMedResource and PubMed.

Other sources of information

• Ettinger S J & Feldman E C (2000) Eds. Textbook of Veterinary Internal Medicine. 5th edn. W B Saunders & Co, USA.
• Kaneko J J, Harvey J W & Brass M L (1997) Eds. Clinical Biochemistry of Domestic Animals. 5th edn. Academic Press, USA.
• Duncan J R, Prasse K W & Mahaffey E A (1994) Veterinary Laboratory Medicine. Clinical Pathology. 3rd edn. Iowa University Press, USA.