Anemia 2: Hemolytic Anemias & Polycythemia

Question 1

Erythrocyte membrane defects, enzyme defects, and hemoglobinopathies all share what pathophysiologic classification? Do they show reticulocytosis?

Answer 1

Hemolytic anemias / Increased RBC destruction; all hemolytic anemias show reticulocytosis

Question 2

Compared to intravascular hemolysis, extravascular hemolysis mainly occurs in what 2 organs?

Answer 2

Spleen and liver

Question 3

Name 3 hereditary erythrocyte membrane defects that cause hemolytic anemia. What parts of their cell structures are defective?

Answer 3

Hereditary spherocytosis, hereditary elliptocytosis, and acanthocytosis; the first 2 involve defects in cytoskeleton while acanthocytosis involves defects in the lipid membrane bilayer

Question 4

Compare and contrast acanthocytes with echinocytes in terms of membrane shape and central pallor.

Answer 4

Acanthocytes / spur cells: spiny projections, no central pallor
Echinocytes / burr cells / crenated cells: more uniform membrane scalloping, maintain central pallor

Question 5

What are the 2 most common RBC enzyme defects, which lead to hereditary non-spherocytic anemias? Which one is X-linked?

Answer 5

G6PD deficiency and pyruvate kinase deficiency; G6PD

Question 6

Describe the formation of “bite cells.” What type of anemia are they associated with? What can precipitate their occurrence?

Answer 6

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

Question 7

Most hemoglobinopathies are associated with point mutations in what part of the hemoglobin molecule?

Answer 7

The β-globin chain

Question 8

Hemoglobinopathy associated with Hb S homozygosity, vaso-occlusive disease, and aplastic crises.

Answer 8

Sickle cell disease

Question 9

Name for the nuclear remnants (DNA clusters) seen in sickle RBCs; they signify the presence of hyposplenism usually due to splenic ischemia

Answer 9

Howell-Jolly bodies

Question 10

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

Answer 10

Sequestration crisis

Question 11

Name this sickle cell associated problem: rapid decrease in respiratory function plus pulmonary infiltrates on chest x-ray

Answer 11

Acute chest syndrome

Question 12

Name this sickle cell associated problem: self-limited swelling of hands and feet due to underlying bone infarcts

Answer 12

Hand-foot syndrome

Question 13

Name this sickle cell associated problem: complication due to Salmonella typhimurium infection

Answer 13

Osteomyelitis

Question 14

Hemoglobinopathy associated with erythrocyte rigidity, mild chronic hemolysis, and normocytic anemia

Answer 14

Hemoglobin C disease (homozygosity)

Question 15

Thalassemia-like hemoglobinopathy associated with microcytic, hypochromic RBCs and mild anemia; 2nd only to Hb S in prevalence in SE Asia.

Answer 15

Hemoglobin E disease (homozygosity)

Question 16

Name the 3 kinds of autoimmune hemolytic anemias, and what kind of anti-RBC immunoglobulin is associated with each.

Answer 16

Warm Antibody AIHA: IgG
Cold Antibody AIHA: IgM
Cold Hemolysin Disease: IgG

Question 17

What kind of agglutination test uses antihuman globulin to check for the presence of antibody on a RBC surface?

Answer 17

Direct Coombs test (indirect Coombs looks for free antibody in the blood)

Question 18

What is the most common type of autoimmune hemolytic anemia, and what RBC antigens are most often targeted?

Answer 18

Warm antibody AIHA; Rh antigens

Question 19

Describe the 3 mechanisms of drug-induced warm antibody autoimmune hemolytic anemias: hapten, immune-complex, and autoantibody.

Answer 19

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

Question 20

In which autoimmune hemolytic anemia is Raynaud’s phenomenon most likely to be observed?

Answer 20

Cold antibody AIHA

Question 21

Which autoimmune hemolytic anemia involves complement activation but not agglutination? What is the associated syndrome?

Answer 21

Cold hemolysin disease; paroxysmal cold hemoglobinuria

Question 22

Which autoimmune hemolytic anemia involves Donath-Lansteiner antibodies that attack the P antigens of RBCs?

Answer 22

Cold hemolysin disease

Question 23

Type of hemolytic anemia where RBCs are attacked by outside/non-self antibodies? What subtype is associated with giving incompatible blood?

Answer 23

Alloimmune hemolytic anemia; hemolytic transfusion reaction

Question 24

Hemolytic anemia where a mother’s antibodies cross the placenta and attack the antigens of a fetus? Is Rh or ABO incompatibility more serious?

Answer 24

Hemolytic disease of the newborn; Rh incompatibility is worse

Question 25

DIC, TTP (thrombotic thrombocytopenic purpura), HUS (hemolytic uremic syndrome), and march hemoglobinuria all belong to what type of anemia?

Answer 25

Microangiopathic hemolytic anemia (due to mechanical RBC fragmentation)

Question 26

Distinguish between the blood of DIC and TTP in terms of coagulation factors and platelets.

Answer 26

Both diseases show problems with platelets, only DIC shows problems with coagulation factors

Question 27

What term describes fragmented RBCs but is not specific for any particular cause?

Answer 27

Schistocytes

Question 28

What nonimmune, episodic, hemolytic anemia involves an increase in RBC sensitivity to complement-mediated lysis? Is it intravascular or extravascular?

Answer 28

Paroxysmal nocturnal hemoglobinuria; intravascular

Question 29

What hemolytic anemia involves defects in the PIG-A gene, GPI anchor protein, “decay acceleration factor” (CD55) and “membrane inhibitor of reactive lysis” (CD59)?

Answer 29

Paroxysmal nocturnal hemoglobinuria

Question 30

What is one similarity and one difference in the mechanisms of hemolysis for paroxysmal cold hemoglobinuria and paroxysmal nocturnal hemoglobinuria?

Answer 30

Both involve complement-mediated hemolysis; PCH has “extra” RBC membrane targeting IgGs while PNH has missing RBC membrane proteins

Question 31

Term for hepatic vein thrombosis, which can occur in paroxysmal nocturnal hemoglobinuria.

Answer 31

Budd-Chiari syndrome

Question 32

Instead of using acidified serum or sucrose hemolysis, how is paroxysmal nocturnal hemoglobinuria diagnosed today?

Answer 32

Flow cytometry (can see loss of GPI/glycosyl phosphatidylinositol protein)

Question 33

Is polycythemia vera an absolute or relative, and primary or secondary polycythemia?

Answer 33

Absolute, primary

Question 34

Is EPO-dependent polycythemia absolute or relative, and primary or secondary?

Answer 34

Absolute, secondary

Question 35

What is the cause of relative polycythemia?

Answer 35

Dehydration