Canis ISSN: 2398-2942

Azotemia

Contributor(s): Martha Cannon, Richard Squires

Introduction

  • Azotemia is an increased concentration of nonprotein nitrogenous compounds (eg urea and creatinine) in the blood. "Uremia" is the clinical syndrome that occurs as a result of severe azotemia due to abnormal renal function.
  • Causes:
    • Reduced glomerular filtration rate:
      • Reduced renal perfusion (pre-renal azotemia Pre-renal azotemia ).
      • Intrinsic renal disease (renal azotemia Uremia ).
      • Obstruction to urinary outflow (post-renal azotemia).
    • Uroabdomen leading to reabsorption of urinary nitrogenous compounds (post-renal azotemia).
    • Increased absorption of nonprotein nitrogenous compounds from the gastro-intestinal tract, eg GI bleeding, high protein meal.
    • Increased protein catabolism, eg fever, trauma, burns Skin: burn / scald , hyperthyroidism.
  • A degree of pre-renal azotemia may be super-imposed on pre-existing renal or post-renal azotemia.
    Follow the diagnostic tree for Azotemia Azotemia.

Pathogenesis

Etiology

Predisposing factors

General

Pathophysiology

  • Post-renal azotemia:refer to urethral obstruction and/or uroabdomen.
  • Renal azotemia:refer to acute renal failure and chronic renal failure.
  • Pre-renal azotemia:
    • Reduced renal perfusion: initially, in the absence of primary renal disease, renal auto-regulatory mechanisms compensate for the tendency to reduce glomerular filtration rate and low vascular volume by increasing sodium and water reabsorption. Urine specific gravity rises to >1.030, if renal function Renal function assessment is adequate.
    • Eventually renal compensatory mechanisms are overwhelmed. Reduced renal perfusion → reduced glomerular filtration rate → reduced renal excretory function → accumulation of toxic metabolites in the circulation, including nonprotein nitrogenous substances → azotemia and eventually uremia.

Diagnosis

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Treatment

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Outcomes

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Further Reading

Publications

Refereed papers

Other sources of information

  • Cowgill L D & Francy T (2005)Acute Uraemia.In:Textbook of Veterinary Internal Medicine, 6th Edition Eds: Ettinger S J, Feldman E C. Elsevier Saunders pp 1731-1751.
  • Squires R A (2005)Laboratory evaluation of renal disorders.In:BSAVA Manual of Canine and Feline Clinical Pathology,2nd Edition. Eds: Villiers E & Blackwood L. BSAVA Publications, Quedgeley. pp 169-183.
  • Polzon D J (2004)Azotemia and Uremia.In:The 5-Minute Veterinary Consult, Canine and Feline.Eds: Tilley L P, Smith F W K, Lippincott, Williams and Wilkins. pp 142-143.
  • DiBartola S P (1995)Urinary Emergencies.In:Handbook of Veterinary Procedures and Emergency Treatment.6th Edition Eds: Bistner S I and Ford R B. W B Saunders Co, Philadelphia. pp 120-124.


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