Felis ISSN 2398-2950

Hemoglobinuria

Introduction

  • Presence of free hemoglobin in the urine.
  • Cause: hemoglobin filtered by the glomeruli (true hemoglobinuria), or hemoglobin released by lysis of erythrocytes in urine (hematuria).
  • Signs: reddish discoloration of urine.
  • Diagnosis: blood reaction on urine test strip; lack of erythrocytes in urine sediment; investigation of cause.
  • Treatment: depends on cause.
  • Prognosis: depends on cause.

Pathogenesis

Etiology

Erythrocyte lysis within urine

Intravascular hemolysis

  • Hemoglobin filtered by glomeruli.
  • Intravascular hemolysis is more likely to result in hemoglobinuria than is extravascular hemolysis.
  • Hemoglobinuria is more likely to result when hemolysis is severe and/or rapid.
  • Idiopathic.
  • Bacterial infection:
  • Red blood cell parasite infection:
  • Chemicals and drugs:
    • Phenothiazine.
    • Methylene blue.
    • Paracetamol Paracetamol.
    • Copper.
    • Ricin.
  • Immune-mediated:
  • Hypo-osmolarity.
  • Cold-induced hemoglobinuria.
  • Increased red cell fragility:
    • Toxemia.
    • Heat stroke.
    • Radiation.

Extravascular hemolysis

Pathophysiology

  • Hemoglobinuria may result from either of two main sources:
    • True hemoglobinuria results when hemoglobin is filtered by the glomeruli.
    • Hemoglobinuria also results from hematuria Hematuria when erythrocytes are lysed within the urine.
  • True hemoglobinuria caused by intravascular or extravascular destruction of erythrocytes   →   release of hemoglobin into plasma.
  • Hemoglobin is a metalloprotein of molecular weight 64,500   →   small enough to pass the glomerular filter.
  • Severe or moderate intravascular hemolysis   →   free hemoglobin appears in urine.
  • Most of the free hemoglobin in urine is probably secreted as a dimer.
  • True hemoglobinuria is usually accompanied by clinical signs of hemolysis.
  • Hemoglobinuria results from hemolysis only when erythrocytes are destroyed at a rate exceeding the capacity of conversion of hemoglobin to bilirubin   →   many patients with hemolysis will have bilirubinemia and icterus rather than hemoglobinuria.

Timecourse

  • A few hours to several weeks, depending on cause and severity.

Diagnosis

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Treatment

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Bobade P A, Nash A R & Rogerson P (1988) Feline haemobartonellosis - clinical, hematological and pathological studies in natural infections and the relationship to infection with feline leukaemia virus. Vet Rec 122 (2), 32-36 VetMedResource.

Other sources of information

  • Loar A S (1994) Anaemia - diagnosis and treatment. In: Consultations in Feline Internal Medicine II Philadelphia: W B Saunders Co, pp.469-487. ISBN 0 7216 4674 3.


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