Anemia 2: Hemolytic Anemias & Polycythemia Flashcards
Erythrocyte membrane defects, enzyme defects, and hemoglobinopathies all share what pathophysiologic classification? Do they show reticulocytosis?
Hemolytic anemias / Increased RBC destruction; all hemolytic anemias show reticulocytosis
Compared to intravascular hemolysis, extravascular hemolysis mainly occurs in what 2 organs?
Spleen and liver
Name 3 hereditary erythrocyte membrane defects that cause hemolytic anemia. What parts of their cell structures are defective?
Hereditary spherocytosis, hereditary elliptocytosis, and acanthocytosis; the first 2 involve defects in cytoskeleton while acanthocytosis involves defects in the lipid membrane bilayer
Compare and contrast acanthocytes with echinocytes in terms of membrane shape and central pallor.
Acanthocytes / spur cells: spiny projections, no central pallor
Echinocytes / burr cells / crenated cells: more uniform membrane scalloping, maintain central pallor
What are the 2 most common RBC enzyme defects, which lead to hereditary non-spherocytic anemias? Which one is X-linked?
G6PD deficiency and pyruvate kinase deficiency; G6PD
Describe the formation of “bite cells.” What type of anemia are they associated with? What can precipitate their occurrence?
Parts of the RBC membrane are removed by the spleen; G6PD deficiency anemia; hemolysis is precipitated by oxidative stress such as eating fava beans or taking antimalarial drugs
Most hemoglobinopathies are associated with point mutations in what part of the hemoglobin molecule?
The β-globin chain
Hemoglobinopathy associated with Hb S homozygosity, vaso-occlusive disease, and aplastic crises.
Sickle cell disease
Name for the nuclear remnants (DNA clusters) seen in sickle RBCs; they signify the presence of hyposplenism usually due to splenic ischemia
Howell-Jolly bodies
Name this sickle cell associated problem: a sudden pooling of RBCs in the spleen of young sickle cell patients, followed by hypovolemic shock and death
Sequestration crisis
Name this sickle cell associated problem: rapid decrease in respiratory function plus pulmonary infiltrates on chest x-ray
Acute chest syndrome
Name this sickle cell associated problem: self-limited swelling of hands and feet due to underlying bone infarcts
Hand-foot syndrome
Name this sickle cell associated problem: complication due to Salmonella typhimurium infection
Osteomyelitis
Hemoglobinopathy associated with erythrocyte rigidity, mild chronic hemolysis, and normocytic anemia
Hemoglobin C disease (homozygosity)
Thalassemia-like hemoglobinopathy associated with microcytic, hypochromic RBCs and mild anemia; 2nd only to Hb S in prevalence in SE Asia.
Hemoglobin E disease (homozygosity)
Name the 3 kinds of autoimmune hemolytic anemias, and what kind of anti-RBC immunoglobulin is associated with each.
Warm Antibody AIHA: IgG
Cold Antibody AIHA: IgM
Cold Hemolysin Disease: IgG
What kind of agglutination test uses antihuman globulin to check for the presence of antibody on a RBC surface?
Direct Coombs test (indirect Coombs looks for free antibody in the blood)
What is the most common type of autoimmune hemolytic anemia, and what RBC antigens are most often targeted?
Warm antibody AIHA; Rh antigens
Describe the 3 mechanisms of drug-induced warm antibody autoimmune hemolytic anemias: hapten, immune-complex, and autoantibody.
Hapten mechanism: drug binds to RBC surface
Immune-complex mechanism: drug reacts with circulating antibody; resulting complex binds to RBCs
Autoantibody mechanism: drug causes formation of cross-reacting antibodies which bind to RBCs
In which autoimmune hemolytic anemia is Raynaud’s phenomenon most likely to be observed?
Cold antibody AIHA
Which autoimmune hemolytic anemia involves complement activation but not agglutination? What is the associated syndrome?
Cold hemolysin disease; paroxysmal cold hemoglobinuria
Which autoimmune hemolytic anemia involves Donath-Lansteiner antibodies that attack the P antigens of RBCs?
Cold hemolysin disease
Type of hemolytic anemia where RBCs are attacked by outside/non-self antibodies? What subtype is associated with giving incompatible blood?
Alloimmune hemolytic anemia; hemolytic transfusion reaction
Hemolytic anemia where a mother’s antibodies cross the placenta and attack the antigens of a fetus? Is Rh or ABO incompatibility more serious?
Hemolytic disease of the newborn; Rh incompatibility is worse
DIC, TTP (thrombotic thrombocytopenic purpura), HUS (hemolytic uremic syndrome), and march hemoglobinuria all belong to what type of anemia?
Microangiopathic hemolytic anemia (due to mechanical RBC fragmentation)
Distinguish between the blood of DIC and TTP in terms of coagulation factors and platelets.
Both diseases show problems with platelets, only DIC shows problems with coagulation factors
What term describes fragmented RBCs but is not specific for any particular cause?
Schistocytes
What nonimmune, episodic, hemolytic anemia involves an increase in RBC sensitivity to complement-mediated lysis? Is it intravascular or extravascular?
Paroxysmal nocturnal hemoglobinuria; intravascular
What hemolytic anemia involves defects in the PIG-A gene, GPI anchor protein, “decay acceleration factor” (CD55) and “membrane inhibitor of reactive lysis” (CD59)?
Paroxysmal nocturnal hemoglobinuria
What is one similarity and one difference in the mechanisms of hemolysis for paroxysmal cold hemoglobinuria and paroxysmal nocturnal hemoglobinuria?
Both involve complement-mediated hemolysis; PCH has “extra” RBC membrane targeting IgGs while PNH has missing RBC membrane proteins
Term for hepatic vein thrombosis, which can occur in paroxysmal nocturnal hemoglobinuria.
Budd-Chiari syndrome
Instead of using acidified serum or sucrose hemolysis, how is paroxysmal nocturnal hemoglobinuria diagnosed today?
Flow cytometry (can see loss of GPI/glycosyl phosphatidylinositol protein)
Is polycythemia vera an absolute or relative, and primary or secondary polycythemia?
Absolute, primary
Is EPO-dependent polycythemia absolute or relative, and primary or secondary?
Absolute, secondary
What is the cause of relative polycythemia?
Dehydration
