This information is provided by Provet for educational purposes only.

You should seek the advice of your veterinarian if your pet is ill as only he or she can correctly advise on the diagnosis and recommend the treatment that is most appropriate for your pet.

Measurement of plasma (or blood) urea concentrations are widely used to aid diagnosis in clinical veterinary practice - but there are several non-disease processes which can cause the amount of urea to fall above or below the "normal range" and these need to be eliminated as causes :

Non-clinical causes of INCREASED blood urea 

• High dietary protein intake
• Inadequate calorie intake
• Prolonged exercise
• Exposure to catabolic drugs (eg corticosteroids)
• Decreased anabolism (eg tetracyclines)

Non-clinical causes of DECREASED blood urea

• Low dietary protein intake
• Use of anabolic drugs (eg anabolic steroids) 

Other Pitfalls in Interpretation to watch out for are :

• Blood strip tests do not give accurate values
• Oxalate anticoagulant in collection bottles will give false high readings
• Exposure to ammonia or tobacco smoke will affect strip tests
• The following drugs have been reported to cause false elevations of BUN
  • Aluminium containing antacids
  • Amphotericin B
  • Arsenicals
  • Bacitracin
  • Calcium containing antacids
  • Cephaloridine
  • Chloral hydrate
  • Chlorthalidone
  • Colistin
  • Corticosteroids
  • Dextrothyroxine
  • Ethacrynic acid
  • Furosemide
  • Gentamicin
  • Indomethacin
  • Kanamycin
  • Magnesium containing antacids
  • Methicillin
  • Methocarbamol
  • Nafcillin
  • Neomycin
  • Nicotinic acid
  • Oxacillin
  • Polymixin B
  • Propranolol
  • Spironolactone
  • Stilbophen
  • Streptokinase
  • Sulfonamides
  • Tetracyclines
  • Triamterene
  • Vancomycin
  • Radiographic contrast media
• The following drugs have been reported to cause a false decrease in blood urea :
  • Mercurials

 Last updated : January 2016