Normocytic anemias with predominant intravascular hemolysis Flashcards

1
Q

An acquired defect in myeloid stem cells that results in the absents of glycosylphosphatiylinositol (GPI), allowing cells to be susceptible to destruction by complement…

A

Paroxysmal Nocturnal Hemoglobinuria (PNH)

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2
Q

What is on the surface of RBCs to protect against complement-mediated damage by the inhibition of C3 convertase?

A

Decay accelerating factor (DAF)

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3
Q

What is the anchoring glycolipid that secures DAF to the RBC?

A

GPI

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4
Q

What does the absence of GPI in paroxysmal nocturnal hemoglobinuria (PNH) lead to?

A

Absence of DAF—leave the cell susceptible to complement-mediated damage

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5
Q

Why is episodic intravascular hemolysis often seen during the night while sleep when patients have paroxysmal nocturnal hemoglobinuria (PNH)?

A

Respiratory acidosis develops with shallow breathing during sleep which activates complement—lysing RBCs, WBCs, and platelets

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6
Q

Intravascular hemolysis seen with paroxysmal nocturnal hemoglobinuria (PNH) can lead to what clinical findings?

A

Hemoglobinemia
Hemoglobinuria
Hemosiderinuria days after hemolysis

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7
Q

What screening test is used to test for paroxysmal nocturnal hemoglobinuria (PNH)?

A

Sucrose test

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8
Q

What confirmatory tests can be used to diagnose paroxysmal nocturnal hemoglobinuria?

A

Acidified serum test

Flow cytometry—detect lack of CD55 (DAF) on RBCs

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9
Q

What is the main cause of death seen with paroxysmal nocturnal hemoglobinuria?

A

Thrombosis of the hepatic, portal, or cerebral veins

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10
Q

What are the 2 major complications seen with paroxysmal nocturnal hemoglobinuria (PNH)?

A

Iron deficiency anemia—due to chronic loss of Hb in urine

Acute myeloid leukemia (AML)

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11
Q

G6PD deficiency allows cells to be susceptible to what?

A

Oxidative stress

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12
Q

What is the by-product of G6PD needed to regenerate reduced glutathione to prevent oxidative stress to cells?

A

NADPH

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13
Q

What are the 2 major variants seen with G6PD deficiency?

A

African variant

Mediterranean variant

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14
Q

What is seen with the African variant of G6PD deficiency?

A

Mild reduction in the half-life of G6PD causing mild intravascular hemolysis with oxidative stress

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15
Q

What is seen with the Mediterranean variant of G6PD deficiency?

A

Markedly reduced half-life of G6PD causing major intravascular hemolysis with oxidative stress

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16
Q

Oxidative stress on hemoglobin causes what to form?

A

Heinz bodies

17
Q

What are some causes of oxidative stress seen in G6PD deficiency?

A

Infection
Drugs (Primaquine, sulfa drugs, dapsone)
Fava beans

18
Q

What type of cells are formed when Heinz bodies are removed from RBCs by splenic macrophages?

A

Bite cells

19
Q

Patient presents with hemoglobinuria and back pain hours after the injection of fava beans. What is the most likely underlying cause of this patient’s presentation?

A

G6Pd deficiency

20
Q

What screening test is used to screen for G6PD deficiency?

A

Heinz preparation

21
Q

An IgG-mediated autoimmune disease that usually involves extravascular hemolysis…

A

Immune hemolytic anemia (IHA)

22
Q

What type of cells are formed when IgG binds RBCs and are consumed by splenic macrophages?

A

Spherocytes

23
Q

What are the 3 associations that can be seen with immune hemolytic anemia (IHA)?

A

SLE (most common cause)
CLL
Certain drugs—penicillin and cephalosporins

24
Q

What drug is known to cause production of autoantibodies that bind self antigens on RBCs?

A

a-methyldopa

25
Q

What are the possible treatments for immune hemolytic anemia (IHA)?

A

Cessation of offending drug
Steroids
IVIG—distractor for spleen
Splenectomy—if needed

26
Q

IgM-mediated immune hemolytic anemia involves fixation of what at cold temperatures of the extremities?

A

Complement

27
Q

What serves as an opsonin for splenic macrophages causing spherocyte formation from RBCs, seen with immune hemolytic anemia (IHA)?

A

C3b

28
Q

How does IgM-mediated immune hemolytic anemia (IHA) lead to intravascular hemolysis (usually involves extravascular hemolysis)?

A

Extreme activation of complement

29
Q

What are the two infections associated with IgM-mediated immune hemolytic anemia (IHA)?

A

Mycoplasma pneumoniae

Infectious mononucleosis

30
Q

What is used to diagnose immune hemolytic anemia (IHA)?

A

Coombs test

31
Q

Describe the two different Coombs test used to diagnose immune hemolytic anemia (IHA)…

A

Direct Coombs test—confirms presence of antibody/complement coated RBCs

Indirect Coombs test—confirms the presence of antibodies in patients serum

32
Q

An intravascular hemolysis that is a result from a vascular pathology causing destruction of RBCs as they pass through circulation…

A

Microangiopathic hemolytic anemia

33
Q

Microangiopathic hemolytic anemia occurs with 3 disorders, what are they?

A

Microthrombi (TTP-HUS, DIC, HELLP)
Prosthetic heart valves
Aortic stenosis

34
Q

What is seen on a blood smear of a patient with microangiopathic hemolytic anemia?

A

Schistocytes

35
Q

A infection of RBCs and the liver with Plasmodium, which is transmitted by the female Anopheles mosquito…

A

Malaria

36
Q

What cuases the intravascular hemolysis and cyclical fever seen with malaria?

A

The rupture of RBCs as part of the Plasmodium life cycle

37
Q

Which species of Plasmodium causes a daily fever seen with malaria?

A

Falciparum

38
Q

Which species of Plasmodium cause fever every other day seen with malaria?

A

Vivax and Ovale

39
Q

When RBCs are infected with malaria, how does this cause extravascular hemolysis with splenomegaly?

A

The RBCs are consumed by the spleen when infected