MLAB 1415-Hematology Keri Brophy-Martinez Chapter 14: Introduction to Hemolytic Anemias

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Text of MLAB 1415-Hematology Keri Brophy-Martinez Chapter 14: Introduction to Hemolytic Anemias

  • MLAB 1415-Hematology

    Keri Brophy-MartinezChapter 14: Introduction to Hemolytic Anemias

  • Hemolytic anemiaAnemia caused by hemolysis of red blood cellsHemolysis is the destruction of erythrocytes resulting in the release of hemoglobinResults in reduction of normal red cell lifespan.Normocytic, normochromic anemiaRBCs are prematurely destroyed

  • Classified bySource of defect causing the hemolysisIntrinsic/extrinsicPoikilocyte presentSchistocytes/SpherocytesMode of onsetInherited/acquiredLocation of hemolysisIntravascular/Extravascular

  • Lab FeaturesReticulocytosisRPI> 2Erythroid hyperplasia of bone marrowM:E ratio decreasedPeripheral bloodNormochromic,normocyticPolychromasianRBCsTests for heme catabolism abnormalUnconjugated/conjugated bilirubinHaptoglobin

  • Lab Features

    Increased Bone Marrow Production of ErythrocytesIncreased Erythrocyte DestructionReticulocytosis (RPI>2)AnemiaLeukocytosisSpherocytes, Schistocytes, PoikilocytesnRBCs in PBDecreased haptoglobinPolychromasiaIncreased bilirubinNormoblastic erythroid hyperplasia in bone marrowIncreased LDHM:E decreasedIncreased urobilinogenIncreased expired COHemoglobinemia*Hemoglobinuria*Hemosiderinuria**Only with intravascular hemolysis

  • Diagnostic Approach to Hemolytic AnemiasIncreased RBC ProductionIncreased RBC DestructionCOOMBS (DAT) testImmune Hemolytic AnemiasPeripheral blood smearRBC MorphologyLab InvestigationDefinitive Diagnosis

  • Clinical FindingsJaundicePallorFatigueCardiac symptomsGallstonesDark or red urineSplenomegaly

  • Sites of DestructionIntravascularHemolysis occurs within the circulationRBCs are severely damagedExtravascularHemolysis occurs within the macrophages of the spleen, liver or bone marrowMore common than intravascular

  • Intravascular Destruction

    RBC is hemolyzedFree hgb released into plasmaHgb binds to haptoglobinIf haptoglobin depleted, hemopexin can step inThis complex goes to liver Complex converted to bilirubinBilirubin excreted to intestinal tract

  • TermsHemoglobinemiaOccurs if hemopexin and haptoglobin is depleted. Free hgb circulates in blood.Hemoglobinuria Occurs if free hgb can not be absorbed by the liver and kidney3. HemosiderinuriaHemosiderin in the urine, sign of filtration of hemoglobin thru the kidney

  • Causes ofIntravascular Hemolysis

    Activation of Complement on RBC MembranePhysical or Mechanical Trauma to the RBCToxic Microenvironment of the RBCParoxysmal noctural hemoglobinuriaMicroangiopathic hemolytic anemiaBacterial infectionsParoxysmal cold hemoglobinuriaAbnormalities of heart vesselsPlasmodium falciparum infectionSome transfusion reactionsDisseminated intravascular coagulationVenomsSome autoimmune hemolytic anemiasThermal injuryAcute drug reaction in G6PD deficiency

  • Extravascular DestructionHgb is degraded within the phagocyte to heme and globinPhagocyte locations:Spleen: removes slightly damaged RBCsLiver: removes severely damaged RBCsBone marrow: remove mature precursor cells that are intrinsically abnormalHeme further degraded to iron, biliverdin and carbon monoxideBiliverdin enters plasma as bilirubinBilirubin binds to albumin, excreted by the liver

  • Causes of Extravascular Hemolysis

    OriginAnemiasInherited RBC DefectsThalassemia, Hemoglobinopathies, Enzyme deficiencies, Membrane disorderAcquired RBC DefectsMegaloblastic anemia, Vitamin E deficiency in newbornsImmunohemolytic anemiasAutoimmune, Drug induced, Some transfusion reactions

  • Source of Defect of RBCIntrinsic Abnormality of the RBCMembraneCell enzymesHemoglobin moleculeUsually hereditaryEXCEPTION: AcquiredParoxysymal noctural hemoglobinuria (PNH)Site of hemolysis: extravascular

  • Source of Defect of RBCExtrinsicAntagonist in cells environment causes injury to the RBCAntagonistic plasma factorsTraumatic physical cell injuryImmune mediated cell destructionRBC is normalUsually acquiredSite of hemolysis: intra or extravascular

  • ReferenesHarmening, D. M. (2009). Clinical Hematology and Fundamentals of hemostasis (5th ed.). Philadelphia, PA: F.A. Davis Company. McKenzie, S. B. (2010). Clinical Laboratory Hematology (2nd ed.). Upper Saddle River, NJ: Pearson Education, Inc..