Ch5 - 6) Normocytic anemia with predominant intravascular hemolysis Flashcards Preview

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What is used to confirm G6PD deficiency? When is it performed?

enzyme studies confirm deficiency (performed weeks after hemolytic episode resolves).


What is immune hemolytic anemia?

Antibody-mediated (IgG or IgM) destruction of RBCs


In IHA what does the IgG-mediated disease usually involve?

extravascular hemolysis.


In IgG mediated IHA how does spherocyte formation result?

IgG binds RBCs in the relatively warm temperature of the central body (warm agglutinin); membrane of antibody-coated RBC is consumed by SPLENIC macrophages, resulting in spherocytes


What is the most common cause of IgG mediated IHA?



What is IgG mediated IHA associated with?

SLE (most common cause), CLL, and certain drugs (classically, penicillin and cephalosporins)


How do certain drugs relate to IgG mediated IHA?

Drug may attach to RBC membrane (e.g., penicillin) with subsequent binding of antibody to drug-membrane complex. 2). Drug may induce production of autoantibodies (e.g., u-methyldopa) that bind self antigens on RBCs


What does the treatment of IgG mediated IHA involve?

cessation of the offending drug, steroids, IVIG, and, if necessary, splenectomy.


What does IgM-mediared IHA disease usually involve?

intravascular hemolysis.


What happens in IgM mediated IHA?

IgM binds RBCs and fixes complement in the relatively cold temperature of the extremities (cold agglutinin).


What is the IgM mediated IHA associated with?

Mycoplasma pneumoniae and infectious mononucleosis


What test is used to diagnose IHA?

Coombs test is used to diagnose IHA; testing can be direct or indirect.


What is the Direct Coombs test?

confirms the presence of antibody-coated RBCs. Anti-IgG is added to patient RBCs; agglutination occurs if RBCs are already coated with antibody.


What is the most important test for IHA?

Direct Coombs test


What is the indirect Coombs test?

it confirms the presence of antibodies in patient serum. Anti-IgG and test RBCs are mixed with the patient serum; agglutination occurs if serum antibodies are present.


What is microangiopathic hemolytic anemia?

Intravascular hemolysis that results from vascular pathology; RBCs are destroyed as they pass through the circulation.


What occurs with chronic hemolysis?

Iron deficiency anemia


Microangiopathic hemolytic anemia occurs with what?

Occurs with microthrombi (TTP-HUS, DIG, HELLP), prosthetic heart valves, and aortic stenosis; microthrombi produce schistocytes on blood smear


What is malaria?

Infection of RBCs and liver with Plasmodium, transmitted by the female Anopheles mosquito


How does malaria affect RBCs?

RBCs rupture as a part of the Plasmodium life cycle, resulting in intravascular hemolysis and cyclical fever.


What does P falciparum present with?

daily fever


What does P vivax and P ovale present as?

fever every other day


What is the role of the spleen in malaria?

Spleen consumes some infected RBCs; results in mild extravascular hemolysis with splenomegaly