内科学教学课件：Hemolysis

HemolysisLearningObjectivesDistinguishextravascularfromintravascularhemolysisRecognizehemolyticanemiabyitsclinicalandlaboratoryfeaturesDiagnosethecommontypesofhemolyticanemiasNormalHypoproliferativeMaturationabnormality

HemolyticMarrowRedcelllifespan–120daysMarrow/CirculatingRedCellRelationshipsInDisturbancesOfTheErythronThedistinguishingfeatureofthehemolyticanemiasistheincreasedrateofdestructionofcirculatingredcells.HemolyticanemiasarerecognizedbyanemiawithsignsofincreasedredcellproductionwhichoccursasthenormalbonemarrowattemptstocompensatefortheacceleratedlossofRBC’s.Peripheralsmear–polychromasiaReticulocytosiswithanelevatedRPIChangesinRBCmorphologyElevatedLDHfromredcellbreakdownIncreaseinhemoglobinbreakdownpigmentsAccompaniedbyintenseerythroidhyperplasiaofthemarrowHowdowediagnosehemolyticanemia?WestartwiththehistoryandphysicalexamWedoacarefulexaminationoftheperipheralsmearWemeasurethereticulocytecountandcalculatethereticulocyteproductionindex(RPI).>3(with1beingbaseline)WesearchforhemoglobinbreakdownpigmentsindicativeofhemolysisScleralIcterusJaundice

duetoincreasedbilipigment–bestseeninthescleraeSplenomegalyOneofthemostconstantfeaturesofextravascularhemolysisItiscausedbyaccelerateddestructionofredcells,mediatedbymacrophagesinthespleen,andsometimestheliverPigmentedGallStonesFromincreasedbilirubincontentofthebile,iftheprocessischronic.PolychromasiaReticulocytescontainalargeamountofRNAwhichstainsbluishredonastandardbloodsmear.BecausethereisashiftofmarrowreticsintothePB,thereispolychromasia.Alsolookforshapechanges.AfterexaminingtheperipheralsmearandcalculatingthereticulocyteindexWemeasure

LDHBilirubinTheunconjugatedbilirubiniselevatedwithextravascularhemolysisWhatisthepredominantsiteofredcellbreakdowninhemolysis?Extravascular–outsidethebloodvesselsWithinmacrophagesintheSpleenLiverCauseshyperbilirubinemiaIntravascular–withinbloodvesselsPlayslittleornoroleinnormalredcelldestruction,butplaysamajorroleincertaintypesofhemolyticanemiaCauseshemoglobinuriaand/orhemosiderinuriaRedCellDestructionbytheReticuloendothelialSystemRBCRECellHbUrobilinogenCO(expired)BilirubinLiverFeTransferrinGlobinAminoAcidPoolFecalUrobilinogenHemoglobinTetramerHemoglobinDimerHEPATOCYTEFeBilirubinHaptoglobinMethemalbuminHemopexinRBCIntravascularRedCellHemolysisMethemoglobinHemeGlobinHemosiderinHemoglobinMethemoglobin012345610HemosiderinuriaIntravascularHemolyticEventLEVELTIME(d)SerumHaptoglobinHemoglobinuriaIndicatorsofIntravascularHemolysisAbsenceofhaptoglobinPresenceoffreehemoglobininserumHemoglobinuria(acute)Hemosiderinuria(chronic)AbsenceofhemopexinPresenceofmethemalbuminSo,oncewehavedeterminedthathemolysisiscausingtheanemia,

howdowedeterminewhatiscausingthehemolysis?

Isitaproblemintrinsictotheredcell,oristheredcellmerelyaninnocentbystanderinahostileenvironment?ClassificationofHemolyticAnemiasIntracellularDefectsMembranedefectMetabolicdefectHemoglobinabnormalityCase#1

A55yomanwasseenforincreasingfatigueoverseveralmonthsHiswifenoticedhehadyelloweyesHisphysiciannotedthathisspleenwaspalpable5cmbelowtheLCBHisHgbwas8gmandhisreticctwas15%.Bilirubinwas3.0T,2.5Ind(elevated)52†Complicationspostsplenectomy407101215AnemiaSplenectomyIntermittentjaundiceGallstonesCardinalFeaturesofHereditarySpherocytosisIncreasedrateofredcelldestructionSpherocytosisSplenomegalyFamilialoccurrenceInvariablebenefitfromsplenectomyPathobiologyofthemembranelesioninHSAbnormalitiesofthecytoskeletalproteinsleadtoverticaluncoupling,withvesicleformationandlossofpiecesofmembrane,leadingtoshapechangeandlossofelasticity.Defectisusuallyautosomaldominant.Somecasesaredoubleheterozygotesforarecessivegene.WhydoessplenectomybenefitpatientswithHS?ClassificationofHemolyticAnemiasIntracellularDefectsMembranedefectMetabolicdefectHemoglobinabnormalityAn18yohealthyAfricanAmericanmalehadthesuddenonsetofnausea,fever,abdominalpainanddarkurineFourdayspreviouslyhehadtakenlargedosesofacetaminophenforaflu-likeillnessPEshowedscleralicterusHgb8g,Reticct12%HeinzBodyprep+Whenquestionedcarefully,herecalledsimilarsymptomsafteraurinarytractinfectiontreatedwithsulfamethoxazoleabout5yrsagoCase#2“Blister”cellswithacutehemolysisafteranoxidantstressinG6PDDeficiencyFromHoffbrand,PettitandMossHeinzBodyPreparationG6PDdeficiencyMostcommoninheritedRBCenzymedeficiencyAffectsover400millionpeopleworldwide.HighestgenefrequenciesfoundintropicalandsubtropicalcountrieswherethedeficiencyoffersprotectionagainstfalciparummalariaIsanexampleofbalancedpolymorphismDiscoveredin1956IndividualsdevelopingHAaftertheantimalarialdrugprimaquinehadlowlevelsofG6PDintheirbloodSubsequentlyasimilaritywasnotedbetweentheHAassociatedwithFavaBeaningestion.G6PDDeficiencyIsx-linked–femalemosaicslesssymptomaticthanaffectedmalesMorethan450biochemicaland140molecularvariants-mostlypointmutationsClassI–severelydeficientduetoclusterofmutationsinexons10and11atNADPorG6PbindingsitesAssociatedwithchronicnon-spherocytichemolyticanemia-uncommonClassII–severelydeficient(1-10%residualactivity)associatedwithacutehemolysisinducedbyoxidativestressMediterraneanvariantwithsensitivitytofavabeans.Neonataljaundicewithdeficiencyinhepatocytes(kernicterus)andRBCs(hemolyticanemia)ClassIII–moderatelydeficient(10-60%residualactivity)African(A-variant).Accountsfor90%ofcasesPresentin10%ofAfricanAmericansDeficiencyonlyinolderRBC’sHemolysisistriggeredbyoxidantdrugsorsevereinfectionsDiagnosisismadebyG6PDassayafterthehemolyticevent

HowdoesG6PDdeficiencycausehemolysis?HexoseMonophosphateShuntG6PDNADPHGSHHeinzBodiesRBCMembraneDamageHeinzBodiesClassificationofHemolyticAnemiasIntracellularDefectsMembranedefectMetabolicdefectHemoglobinabnormalitySickleCellAnemia

Over200,000birthsannuallyworldwideSicklecellanemiaiscausedbythepresenceofamutanthemoglobinthatformsrigidaggregateswheninthedeoxyform.ThemutationinhemoglobinSHemoglobinScontainsavalineinsteadofaglutamicacidatposition6onthebetachain.DuetothereplacementofadeninebythymineInthedeoxyconfirmation,theBeta6valinebecomesburiedinahydrophobicpocketonanadjacentBetachain,joiningthetwomoleculestogetherThisstronginteractiondoesnotoccurwhenthemoleculeisintheoxyconfirmationThepolymerizationofdeoxyhemoglobinSWhentheSSredcellisplacedinanenvironmentwhereitlosesitsoxygen,clustersofdeoxyHgbSform,polymerize,andalignthemselvesinlongcable-likestructures.TherateofformationofthepolymersisexquisitelydependentonconcentrationofdeoxyHgbSintheredcell.AnirreversiblysickledcellThesebundlesoffiberdeformthecellintoanirregularrodorcrescentresemblingasickle.Polymerformationisreversiblewithoxygenation,butthemembranedamageitcausesisirreversibleandthesickledcellisdestinedforearlydestruction.InhibitionoftheformationofthesebundlesthroughmanipulationofHgbSconcentrationhasbeenamajorfocusoftherapeuticeffortstopreventsickling.PathophysiologyofSickleCellAnemiaSicklecellanemiaisachronicinflammatorystate,punctuatedbyanacuteincreaseininflammationinvolvingparticipationbythefollowingelements.EndotheliumWhitebloodcellsPlateletsCoagulationfactorsOtherplasmaproteinsAdhesionmoleculesDerangementsinnitricoxidemetabolismTheseparticipatealongwithhemoglobinpolymerizationtocausechronicanemiapunctuatedby“crises”termedPainfulvasoocclusiveHemolyticAplasticSequestrationWilliamsHematologyMcGrawHill8thed,2010,pg714DiagnosisofSickleCellAnemia

Thesicklingphenomenoncanbedemonstratedinvitrobyaddingareducingagenttowholeblood.ThediagnosisismadebydoingafunctionaltestforsicklingandbyrunningahemoglobinelectrophoresiswhichdemonstratesthepresenceoftheabnormalbandofhemoglobinSandtheabsenceofhemoglobinA. TreatmentofSickleCellAnemiaTransfusiontherapyisakeyinterventionindecreasingmorbidityandmortalitybyPreventionofneurologicandperioperativecomplicationsTreatmentofacutechestsyndromeTreatmentofacuteanemiaHydroxyureaistheonlytherapythathasbeenshowntobeefficaciousHydreaenhancessurvivalinSickleCellAnemiaVoskaridouetalBlood25Mar2010ClassificationofHemolyticAnemiasExtracellularDefectsFragmentationsyndromesAutoimmunehemolyticanemiaInfectionsHypersplenismCase#3A60yowomancomplainedofincreasingfatigue,DOEandweaknessShehadhadanaorticball-valveprosthesisplaced20yrspreviouslyPErevealedscleralicterus,aspleentipandaloudmurmurofaorticinsufficiencywithsignsofcongestiveheartfailureHerHgbwas7gm.Reticct20%.FragmentationsyndromesMacroangiopathicAorticvalvularhemolysisMicroangiopathicTTPDeficiencyofmetalloproteaseADAMTS-13withresultantverylargeVWFmultimerswhichinduceplateletaggregationandresultinmicrothrombiunderhighshearstressconditionsClassificationofHemolyticAnemiaExtracellulardefectsFragmentationsyndromesAutoimmunehemolyticanemiaHypersplenismInfectionsCase#4Apreviouslyhealthy35yowomandevelopedjointswelling/painandfatigueoveraperiodof2-3monthsPErevealedamalarrash,swellingofthehandsandwrists,scleralicterusandpalpablespleenHgb10gReticct15%DirectCoombstestpositiveTheCoombs’TestThedirectCoombs’testisthehallmarkofautoimmunehemolyticanemiaItdetectsthepresenceofantibodiesboundtotheredcellsurfaceAutoimmuneHemolyticAnemiaAutoantibodiesArecausedbyantibodyproductionbythebodyagainstitsownredcells.ArecharacterizedbyapositivedirectantiglobulintestknownastheCoombs’testAredividedintowarmandcoldtypes,dependingonwhethertheyreactmorestronglywithredcellsatbodytemperatureorinthecoldAutoimmuneHemolyticAnemiasWarmantibodytype–mostcommonDATpositiveforIgGSplenicdestruction(Splenomegaly)Steroidresponsive.SplenectomymaybenecessaryColdagglutinintypeDuetoIgMabs–bindtoRBCsbestat4CFixComplement.DATpositiveforC3BothintravascularandextravascularhemolysisoccurMaycauseacrocyanosis(Raynauds)AremoredifficulttotreatMicroagglutinatesinapatientwithcoldagglutininhemolyticanemiaDruginducedimmunehemolysisAvarietyofdrugsproducepositiveCoombs’tests–sometimeswithoverthemolyticanemiaOver100drugshavebeenimplicatedAntimicrobialsaccountfor>40%Themostfrequentlyassociatedwithhemolysisarecefotetan,ceftriaxoneandpiperacillin.HemolysisstopswithremovalofthedrugC