6.5.2 Hemolytic Anemia Flashcards

1
Q

You suspect hemolytic anemia in your patient who presents with Hgb 6.3, recent fatigue, and increased __________________________, or evidence of _________________________________.

A
  • You suspect hemolytic anemia in your patient who presents with Hgb 6.3, recent fatigue, and:
    • increased reticulocyte count without evidence of bleeding or after correction of iron/nutritional deficiency, or
    • evidence of RBC destruction with increased LDH and bilirubin, decreased haptoglobin, and alteration in RBC shape on peripheral smear
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2
Q

Name the 5 categories of etiologies for hemolytic anemia

A
  • Intracorpuscular vs extracorpuscular defects
  • Inherited vs acquired defects
  • Acute vs chronic
  • Immune vs non-immune destruction
  • Intravascular vs extravascular
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3
Q

Describe the following:

  • Intracorpuscular etiology of hemolytic anemia
  • Mostly inherited or acquired?
  • 5 main types of intracorpuscular causes
A
  • Intracorpuscular etiology of hemolytic anemia
    • Defects in the RBC itself that result in lysis
  • Mostly inhereited
  • Types of intracorpuscular causes
    • Enzyme deficiencies
      • G6PD or pyruvate kinase deficiency
        • affect metabolic capacity including transport and recovery
    • Hemoglobinopathies
      • Sickle cell disease
      • Thalassemia
    • Membrane defects
      • Hereditary spherocytosis, elliptocytosis, tomatocytosis
        • Alterations in RBC shape or membrane function
    • Paroxysmal nocturnal hemoglobinuria
      • Acquired
    • Alpha thalassemia
      • Acquired d/t myelodysplasia
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4
Q

Describe the following:

  • Extracorpuscular etiology of hemolytic anemia
  • Mostly inherited or acquired?
  • 7 main causes of extracorpuscular HA
A
  • Extracorpuscular etiology of hemolytic anemia
    • Normal RBCs destroyed by mechanical, immunologic, infectious, or metabolic alterations
  • Mostly acquired
  • 7 main causes of extracorpuscular HA
    • Antibodies directed at RBC membrane
      • Autoimmune / alloimmune
      • Transfusion rxn (acute/delayed)
      • Drug-induced
    • Mechanical stress
      • Valve disease
      • Device implants
      • Platelet microthrombi in TTP/HUS/DITMA
      • DIC: intravascular fibrin stranding
      • Thermal burns
    • Hypersplenism
      • Causes trapping and destruction
    • Infection
    • Hereditary TTP
    • Oxidant agents on metabolic defect
    • Central toxins, venom, copper poisoning (Wilson’s dz)
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5
Q

Your patient has an immune mediated hemolytic anemia. How is this caused?

How will you identify it?

A
  • Immune mediated
    • RBC destruction caused by antigen-antibody complexes and/or
    • Complement proteins (membrane attack complexes)
  • Direct or Indirect Coombs test
    • Can detect presence of immune complexes directed against RBC globulins
  • Causes
    • Autoimmune hemolytic anemia, drug-induced hemolysis, hemolytic transfusion reaction, cold agglutinins dz
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6
Q

Describe the following:

  • Intravascular etiology of hemolytic anemia
  • Examples of causes
  • Signs/Dx
  • Consequences
A
  • Intravascular etiology of hemolytic anemia
    • Occurs within the circulation, when there is significant membrane structural damage or when the RES is overwhelmed
  • Examples of causes
    • Trauma, shear stress
    • Thermal burns
    • Complement induced lysis
    • Toxins
    • Thrombotic microangiopathies
    • Acute txfn rxn
    • Rh immune globulin (used for tx ITP)
  • Signs/Dx
    • Free serum hgb or heme (products of hemolysis directly into bloodstream)
    • Urinary hemoglobin, heme, hemodiserin
    • Dark urine
    • Oxyhemoglobin pink-tinged blood
    • Mehemoglobin dark-tinged blood
  • Consequences
    • AKI, DIC, increased risk of thrombosis d/t free Hgb or heme
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7
Q

Describe the following:

  • Extravascular etiology of hemolytic anemia
  • RES
  • Consequences
A
  • Extravascular etiology of hemolytic anemia
    • Occurs via macrophages within the reticuloendothelial system
  • RES
    • Liver, spleen, bone marrow, lymph nodes
  • Consequences
    • Damaged RBCs
    • RBCs coated in complement
    • Alterations in RBC shape or reduced malleability (spherocytosis, sickle cells)
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8
Q

Your patient has an anemia with elevated retics, and no clear source of bleeding or dietary deficiency. How will you proceed with dx workup?

A
  • Treatment first if life-threatening anemia
    • Transfusion for severe symptomatic anemia
    • Plasmapheresis for TTP
    • Hydration/diuresis for acute transfusion reaction
  • H & P
    • Onset of sx
    • Recent transfusion? Last 4 wks (delayed onset?)
    • New medication - esp if G6PD deficiency is suspected
    • Hx of hemolytic anemia or fam hx of anemia
    • Splenomegaly, hepatomegaly
    • Presence of jaundice or scleral icterus
    • Dark urine
  • Lab tests
    • If NO obvious cause based on presentation and initial symptoms:
      • Start with direct antiglobin test (Coombs test)
      • Will test for IgG or complement attached to RBC, will help distinguish btwn immune and non-immune mediated hemolysis
    • Hgb, reticulocytes
    • Lactate dehydrogenase (up)
    • Haptoglobin (down)
    • Increased unconjugated bilirubin
    • Peripheral blood sphere
      • Schistocytes, likely TMA
      • Sphero, ellipto, stomatocytes: Inherited RBC dysmorphology
      • Sickle cells or thalassemia
  • Other causes
    • Direct parasitization (malaria, babesiosis, bartonellosis, leishmaniasis)
      • Malaria can also cause hypersplenism causing an additional extravascular hemolysis
    • Bactrerial infxn (clostridium, Haem B)
    • Liver disease > splenomegaly d/t portal htn > RBC membrane alteration in target cells, spur cells, burr cells, stomatocytes
    • Renal dz > fragmentation in microvasculature, uremic plasma, hemodialysis
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