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Heme/Lymph > Hemolytic Anemia > Flashcards

Hemolytic Anemia Flashcards

1
Q

Hemolytic anemia is RBC destruction resulting in…(2)

A

Loss of RBC mass

Release of cellular contents

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2
Q

What types of inherited disorders cause hemolytic anemia?

A

RBC membrane disorders

RBC enzyme deficiencies

Hemoglobinopathies

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3
Q

What types of acquired disorders cause hemolytic anemia?

A
  • Autoimmune (antibody mediated) hemolysis
  • Mechanical trauma
  • Infections
  • Chemical disorders
  • Splenic Sequestration
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4
Q

Is hemolysis more common extravascularly or intravascularly?

A

Extravascularly (Spleen > liver, bone marrow)

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5
Q

What is the difference between extravascular and intravascular autoimmune hemolysis?

A

Extravascular involves antibodies

Intravascular involves complement

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6
Q

Which types of pathologic hemolysis can be both extravascular and intravascular?

A

RBC enzyme disorders

Sickle cell anemia

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7
Q

Which types of pathologic hemolsis disorders are only extravascular? Which are only intravascular?

A
  • Extravascular
    • RBC membrane disorder
    • Thalassemia
  • Intravascular
    • Paroxysmal nocturnal hemoglobinuria
    • Mechanical trauma
    • Malaria
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8
Q

What findings in a laboratory evaluation are associated with hemolysis?

A
  • Reticulocytosis (increased reticulocytes)
  • Increased LDH, AST, potassium (released cellular content)
  • Bilirubinemia - Unconjugated (indirect) or conjugated (with liver disease)
  • Hemoglobinemia (free hgb in plasa)
  • Decreased haptoglobin (scavenges free hgb)
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9
Q

What test is ordered to check for an autoimmune hemolytic disorder?

A

DAT (direct antiglobulin test)

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10
Q

Describe hemoglobinuria and hemosiderinuria

A
  • Hemoglobinuria - Intravascular process (mostly) where Hgb is not scavenged by haptoglobin
  • Hemosiderinuria - Intravascular process (mostly) where iron deposits in renal epithelium, then shed in urine
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11
Q

What is a false hyperkalemia?

A

Phlebotomy induced hemolysis

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12
Q

Why is spectrophotometry sometimes faulty in analyzing hemoglobin levels?

A

Hemoglobin absorbs at measured wavelengths, therefore, many assay produce falsely increased results in the setting of hemolysis

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13
Q

Common symptoms in hemolytic anemia (regardless of etiology)

A

Anemia (obvi)

Hyperbilirubinemia

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14
Q

Symptoms of anemia are more related to _____ of hemolysis

A

acuity (compare to baseline levels)

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15
Q

Assuming a starting point at normal hemoglobin levels, describe the symptoms and signs associated with the following changes?

  • <20% hemolysis (>11g/dL hgb):
  • 20-30% hemolysis (10-11g/dL hgb):
  • 30-40% hemolysis (8-9 g/dL hgb):
  • >40% hemolysis (<8 g/dL hgb):
A
  • <20% hemolysis (>11g/dL hgb):
    • Restlessness
  • 20-30% hemolysis (10-11g/dL hgb):
    • Anxiety, dyspnea with exertion
    • Orthostatic hypotension; tachacardia with exertion
  • 30-40% hemolysis (8-9 g/dL hgb):
    • Syncope
    • Orthostatic hypotension, tachycardia at rest
  • >40% hemolysis (<8 g/dL hgb):
    • Confusion, shock
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16
Q

Indirect bilirubin > 5mg/dL is almost always concurrent with ______ ______

A

liver disease

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17
Q

What risks are associated with hyperbilirubinemia and at what levels of bilirubin do they occur?

A

Jaundice (>2.5 mg/dL)

Scleral icterus (>1.7 mg/dL)

Increased risk of bilirubin gallstone (pigmented)

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18
Q

What are some rare complications of hemolytic anemia?

A
  • Pigment induced kidney injury (tubular obstruction, vasoconstriction)
  • Folate deficiency due to increased utilization
  • Increased risk of venous and arterial thrombosis of atypical sites
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19
Q

What are some clinical features associated with…

  • Extra-medullary hematopoiesis (Thalassemia, hereditary spherocytosis):
  • Beta thalassemia major:
  • Sickle cell anemia:
A
  • Extra-medullary hematopoiesis (Thalassemia, hereditary spherocytosis):
    • Splenomegaly and hepatomegaly
  • Beta thalassemia major:
    • Skeletal changes related to expansion of marrow - “chipmunk facies”
  • Sickle cell anemia:
    • Asplenia
20
Q

What are some clinical features of Microangiopathic Hemolytic Anemia?

A
  • Microvascular infaction causing acute kidney injury
  • Liver disease
  • Abdominal pain
  • Fever
  • Mental status changes
  • Thrombocytopenia
  • Rash
  • Hemorrhagic diarrhea
21
Q

Hereditary spherocytosis

  • Inheritance:
  • Defect:
  • Lab diagnosis:
  • Unique clinical features:
A
  • Inheritance: 75% autosomal dominant; 25% sporadic
  • Defect: Defect in ankyrin, band 3, band 4.2 or α/ß-spectrin leads to weakened or absent spectrin causing weakened cytoskeleton
  • Lab diagnosis: Blood smear review
  • Unique clinical features: Splenomegaly - aplastic crises caused by parvovirus
22
Q

Sickle cell anemia

  • Inheritance:
  • Defect:
  • Lab diagnosis:
  • Unique clinical features:
A
  • Inheritance: Autosomal
  • Defect: Point mutation in ß-hgb chain (chrms 11)
  • Lab diagnosis: Hgb HPLC to identify HbS
  • Unique clinical features: Pain crises; acute chest syndrome; stroke; asplenia
23
Q

Thalassemia

  • Inheritance:
  • Defect:
  • Lab diagnosis:
  • Unique clinical features:
A
  • Inheritance: Autosomal
  • Defect: Decreased production of ß or α hgb chains
  • Lab diagnosis: Elevated hgb A2 for beta-thal trait; gene sequencing; smear review
  • Unique clinical features: Secondary hemochromatosis; skeletal deformities (due to marrow expansion)
24
Q

G6PDH deficiency

  • Inheritance:
  • Defect:
  • Lab diagnosis:
  • Unique clinical features:
A
  • Inheritance: X-linked
  • Defect: Deficiency in G6PDH enzyme - Deficient RBCs cannot reduce oxidant stresses and accumulate, denature, form precipitated hgb (Heinz bodies) - cause lysis or removed in spleen
  • Lab diagnosis: Blood smear review for bite cells
  • Unique clinical features: Males preferentially affected; hemolysis dependent on inciting oxidant stresses
25
Q

Paroxysmal Nocturnal Hemoglobinuria

  • Pathophysiology:
  • Lab diagnosis:
  • Unique clinical features:
A
  • Pathophysiology: Stem cell with deficiency in GPI-linked proteins including the anti-complement proteins CD55 and CD59 on RBCs and WBCs
  • Lab diagnosis: Flow cytometry for CD55 and CD59
  • Unique clinical features: Hypercoagulability (thrombi at unusual sites); may have accentuation of lysis at night
26
Q

Warm autoimmune hemolytic anemias

  • Pathophysiology:
  • Lab diagnosis:
  • Unique clinical features:
A
  • Pathophysiology: RBC autoantibodies that react at 37º causing intravascular coating of RBCs and extravascular lysis in spleen
  • Lab diagnosis: Smear review for spherocytes; DAT
  • Unique clinical features: Splenomegaly; seen in association with B-cell lymphoproliferative disorders
27
Q

Cold autoimmune hemolytic anemia

  • Pathophysiology:
  • Lab diagnosis:
  • Unique clinical features:
A
  • Pathophysiology: RBC IgM autoantibodies that react at <30º and may lead to extravascular hemolysis in the spleen or liver
  • Lab diagnosis: Smear review for spherocytes; DAT
  • Unique clinical features: Rarely clinically significant; Raynaud phenomenon associated with Mycoplasma infections and EBV infections
28
Q

Microangiopathic hemolytic anemia

  • Pathophysiology:
  • Lab diagnosis:
  • Unique clinical features:
A
  • Pathophysiology: Traumatic shearing and subsequent lysis of RBCs due to malfunctioning heart valve or vascular obstruction by microthrombi
  • Lab diagnosis: Smear review for schistocytes; ADAMTS-13 activity; coagulation tests
  • Unique clinical features: DIC; TTP (thrombotic throbocytopenia purpura); Metastatic carcinoma; malignant hypertension
29
Q

Malaria/Babesia

  • Pathophysiology:
  • Lab diagnosis:
  • Unique clinical features:
A
  • Pathophysiology: Intracellular parasites infect the RBC and cause lysis
  • Lab diagnosis: Smear review (thick and thin); PCR for parasites
  • Unique clinical features: Cyclic fever; cerebral malaria; Blackwater fever
30
Q

What are spherocytes?

A
  • Normal sized RBCs with increased hemoglobin concentration
  • Less flexible, trapped in the spleen
  • Shortened life span
31
Q

What are three causes of spherocytes in the blood?

A
  • Thermal injury
  • Intrinsic abnormalities
  • Immune hemolysis
32
Q

What protein most commonly has a defect in Hereditary spherocytosis?

A

Ankyrin (though most patients have deficiencies in both ankyrin AND spectrin)

33
Q

How is Hereditary spherocytosis managed?

A
  • Removal of gallbladders in younger patients
  • Folate supplementation in aplastic crisis
  • Splenectomy: Complete (in adults) and partial (in children < age 6)
34
Q

Warm-autoantibody type represents ___% of the autoimmune hemolytic anemias

A

80%

35
Q

What are some secondary causes of Warm autoantibody type hemolytic anemia?

A
  • Lymphoproliferative disorders
  • Autoimmune disorders
  • Non-hematopoietic neoplasms (Ovarian cancer)
  • Drugs (methyldopa; cephalosporins)
36
Q

What are some secondary causes of cold-autoantibody type hemolytic anemias?

A
  • Postinfectious (Infectious mononucleosis)
  • Lymphoproliferative disorders
37
Q

What type of immunoglobulin is associated with cold AIHA? What is the mechanism?

A
  • IgM - RBC agglutination impedes blood flow in superficial distant vessels
  • Igm and complement mediate RBC injury (intravascular hemolysis)
38
Q

What immune cells are associated with Warm AIHA?

A

IgG or Complement mediated (extravascular hemolysis)

39
Q

Blood smear findings in Warm/Cold AIHA?

A

Spherocytes

Polychromatisa

Agglutinins (Cold)

40
Q

Acute vs Chronic Cold AIHA?

A
  • Acute form occurs 2-3 weeks into infectious illness (EBV/Mycoplasma)
  • Chronic form is associated with lymphoproliferative disorders
41
Q

A G6PDH deficiency results in decreased _______ production and an inability to reduce _______ _______

A

glutathione; oxidant stressors

42
Q

What are heinz bodies (in G6PDH deficiency)?

A

Denatured hemoglobin that directly damages the RBC causing intravascular hemolysis

Heinz bodies are removed in the spleen

43
Q

What are oxidant stressors in a G6PDH deficiency?

A

Infection

Fava beans

Drugs (Dapsone, sulfonamides, primaquine, nitrofuantoin, quinolones)

44
Q

What are the differences between the following G6PD variants in terms of hemolysis and population affected?

  • G6PD A (normal):
  • G6PD B (normal):
  • G6PD A-:
  • G6PDMED:
  • G6PDCANTON:
A
  • G6PD A (normal): No hemolysis; Blacks (20% AA)
  • G6PD B (normal): No hemolysis; All races
  • G6PD A-: Moderate hemolysis; Blacks (11% AA)
  • G6PDMED: Severe hemolysis; Whites
  • G6PDCANTON: Moderate hemolysis; Asian
45
Q

In G6PD A-, what is the difference between new RBCs and old RBCs due to an unstable enzyme?

A

100% acitivity in new RBCs

5-15% activity in “old” RBCs (120 day lifespan normally)

46
Q

How are G6PDH deficiencies screened for today? How are they measured?

A

NADPH fluorescence

Normal, Deficient (intermediate), and Grossly deficient (Low)

In Males: Low OR Normal (during hemolytic rxns)

In Female carriers: Normal, intermediate, or low dependent (on X-inactivation)

47
Q

Paroxysmal Nocturnal Hemoglobinuria is an acquired mutation in the ____ gene

A

PIGA (X chromosome)

Heme/Lymph (18 decks)

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