Hemolytic Anemia

Question 1

Types of hemolytic anemia

Answer 1

• type: spherocyte vs non-spherocyte
• site: intramedullary vs extramedullary
• if extramedullary, then intravascular vs extravascular
• mechanism: immune-mediated or nonimmune mediated
• intrinsic vs extrinsic to the erythrocytes

Question 2

Spherocytic hemolytic anemia

Answer 2

• membrane defect

- acquired by warm autoimmune hemolytic anemia or congenital as in hereditary spherocytosis

Question 3

Nonspherocytic hemolytic anemia

Answer 3

• bite cell hemolysis: oxidant stress from G6PD def

- fragmentation hemolysis as in TTP

Question 4

Intramedullary hemolysis

Answer 4

-associated with disorders of ineffective erythropoeisis including thalassemia

Question 5

Extramedullary hemolysis

Answer 5

• may be extravascular as in hemolysis mediated by the spleen
• may be intravascular as in hemolysis associated with cold agglutinin disease or TTP

Question 6

Immune mediated hemolysis

Answer 6

-identified by Coombs test: direct anti globulin test that detects IgG or complement on the erythrocyte surface

Question 7

Intrinsic erythrocyte hemolysis

Answer 7

-includes membrane defects, enzymopathies, hemoglobinopathies

Question 8

Tests for hemolytic anemia

Answer 8

• combs test: warm antibody autoimmune hemolytic anemia
• osmotic fragility test: hereditary spherocytosis
• cold agglutinin measurement: cold agglutinin autoimmune hemolytic anemia
• hemoglobin electrophoresis: thalassemia or other hemoglobinopathy
• G6PD activity: measure enzyme activity after 2-3 months of hemolytic episode. Levels will be normal during hemolytic episode
• flow cytometry for CD55 and CD59: paroxysmal nocturnal hemoglobinuria

Question 9

Peripheral blood smear findings

Answer 9

• schistocytes and thrombocytopenia: TTP-HUS, DIC, HELLP
• schistocytes in patient with heart valve: valve leak
• erythrocyte agglutination: cold agglutinin hemolysis(mycoplasma, lymphproliferative diseases, CLL)
• spherocytes: autoimmune hemolytic anemia or hereditary spherocytosis
• target cells: thalassemia, liver dz, other hemoglobinopathy
• bite cells: G6PD def

Question 10

Treatment of hemolytic anemia

Answer 10

• warm ab and cold agglutinin autoimmune hemolytic anemia: initial therapy is steroids, splenectomy if steroids are ineffective
• TTP: emergent plasma exchange
• chronic hemolytic anemia: folic acid supplements
• severe anemia in critically ill patients: transfusion
• hereditary spherocytosis and transfusion dependent thalassemias: splenectomy is first line
• severe thalassemia: stem cell transplant
• severe paroxysmal nocturnal hemoglobinuria: stem cell transplant
• ALL patients with hemolytic anemia need daily folic acid

Question 11

Clinical history to suggest hereditary spherocytosis

Answer 11

-family history of jaundice, anemia, splenomegaly, gallstones suggests hereditary spherocytosis

Question 12

Findings in hemolytic anemia

Answer 12

• anemia, splenomegaly, elevated retic count, LDH, indirect bili, decreased haptoglobin
• MCV often elevated due to reticulocytosis