Clinical Pathology 3: Bilirubin And Hemolytic Anemia Flashcards
Approximately 1% of RBC are destroyed and replaced daily. What does it mean when the rate is greater than 1%?
Hemolysis
What is hemolysis
Processing of a RBC by a macrophage
What are the two types of hemolysis
- Extravascular
- Intravascular
Extravascular hemolysis
RBC destruction occurs outside of the blood vessels via phagocytosis by macrophages
Intravascular hemolysis
RBC destructions occurs within the blood vessels.
Hemoglobin from Intravascular hemolysis can result in what?
Injury to tissue (hemoglobinuric nephrosis)
- Must be scavenged by the body before damage occurs
When a red blood cell is digested by a macrophage what is the waste product?
Unconjugated bilirubin
Icteric
Jaundice
What is haptoglobin?
The scavenging system for hemoglobin
— haptoglobin bind hemoglobins and takes it to the liver to be processed into billirubin
What will the plasma and urine look like when hemoglobin<haptoglobin
Normal
If there is more hemoglobin than haptoglobin What are the potential outcomes?
- Hemoglobinemia
- Hemoglobinuria
What is hemoglobinemia?
Red plasma
- Intravascular hemolysis
What is hemoglobinuria
Red urine from freely floating hemoglobin passing through the glomerulus into the urine
- From Intravascular hemolysis
What is hyperbilirubinemia?
Too much billirubin in the blood from either Extravascular or intravascular hemolysis
What is Bilirubinuria?
Presence of billrubin in the urine
Causes of hemolysis
Infection, Oxidative injury, immune-mediated RBC destruction
Hemolysis caused by infection: identification method
Blood smear: characteristic RBS parasites
Hemolysis caused by infection: causes
Infectious agents (Ex: Anaplasma)
Forms of hemolysis caused by infectious agents
Intravascular hemolysis: RBC membrane instability
Extravascular hemolysis: Splenic macrophage identifying infected cell and phagocytes
Hemolysis caused by oxidative injury: Causes
- Ingestion of: garlic, onions zinc (dogs), Tylenol (cats), red maple leaves (horses), Copper( sheep and goats
- CRI of propofol
Hemolysis caused by oxidative injury: diagnostic method
Blood smear:
- Heinz bodies
- Eccentrocytes
- Pyknocytes
- Ghost cells
Hemolysis caused by Immune-mediated destruction: What happens?
Anti-RBC antibodies are formed and attach to surface of RBC.
Hemolysis caused by Immune-mediated destruction: Results
- Complete phagocytosis by splenic and hepatic macrophages (EVH)
-Partial phagocytosis by splenic and hepatic macrophages. Bites off part of RBA membrane —> sphere types (EVH)
-MAC formation (IVH)
Hemolysis caused by Immune-mediated destruction: causes
- Primary autoimmune
- Secondary autoimmune (due to drugs)
— Penicillin in horses, phenobarbital
-Alloantibodies
What is an alloantibody
Where antibodies attack RBC
- Maternal antibodies via colostrum attack kitten/foal RBC
- Incompatible blood transfusion
Hemolysis caused by Immune-mediated destruction: laboratory findings / Diagnosis method
Blood smear:
- Spherocytes (difficult to recognize on cats and horse as they have little central pallor)
Positive direct anti globulin test:
- recognizes Antibody on RBC surface
Auto-agglutination
Immune-mediated anemia:
IgM autoantibody, cross links to other RBCs via antibody
-Strongly regenerative anemia
Fasting hyperbilirubinemia
-Horses and Sm Ru
-Increased bilirubin bc hepatocytes are busy metabolizing Fat
- INcreased Unconjugated bilirubin
