ANEMIA贫血.docx

ANEMIA贫血.docx

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ANEMIA贫血

Whatisanemia?

•Definedbymeasurementofhemoglobinconcentration

¡Normal–15g/dlinmales;14g/dlinfemales

¡Patientsare“anemic”whenhgbis>2standarddeviationsbelownormal

¡DeterminingreticulocytecountandMCVarefirststepsindeterminingetiology

•Almost1/3oftheworldpopulationisanemic!

（A）Inheritedhaemolyticanemia

WhatIsSickleCellAnemia?

Sicklecellanemiaisthemostcommonformofsicklecelldisease（SCD）.SCDisaseriousdisorderinwhichthebodymakessickle-shapedredbloodcells.“Sickle-shaped”meansthattheredbloodcellsareshapedlikeacrescent.

WhatCausesSickleCellAnemia?

Sicklecellanemiaisaninheriteddisease.Peoplewhohavethediseaseinherittwogenesforsicklehemoglobin—onefromeachparent.

Sicklehemoglobincausesredbloodcellstodevelopasickle,orcrescent,shape.Sicklecellsarestiffandsticky.Theytendtoblockbloodflowinthebloodvesselsofthelimbsandorgans.Blockedbloodflowcancausepainandorgandamage.Itcanalsoraisetheriskforinfection.

WhatAretheSignsandSymptomsofSickleCellAnemia?

∙Thesignsandsymptomsofsicklecellanemiavary.Somepeoplehavemildsymptoms.Othershaveveryseveresymptomsandoftenarehospitalizedfortreatment.

∙Sicklecellanemiaispresentatbirth,butmanyinfantsdon'tshowanysignsuntilafter4monthsofage.

∙Themostcommonsignsandsymptomsarelinkedtoanemiaandpain.Othersignsandsymptomsarelinkedtothedisease'scomplications.

SignsandSymptomsRelatedtoAnemia

Themostcommonsymptomofanemiaisfatigue（feelingtiredorweak）.Othersignsandsymptomsofanemiainclude:

∙Shortnessofbreath

∙Dizziness

∙Headaches

∙Coldnessinthehandsandfeet

∙Palerthannormalskinormucousmembranes（thetissuethatlinesyournose,mouth,andotherorgansandbodycavities）

∙Jaundice（ayellowishcoloroftheskinorwhitesoftheeyes）

SignsandSymptomsRelatedtoPain

∙Suddenpainthroughoutthebodyisacommonsymptomofsicklecellanemia.Thispainiscalledasicklecellcrisis.Sicklecellcrisesoftenaffectthebones,lungs,abdomen,andjoints.

∙Thesecrisesoccurwhensickledredbloodcellsblockbloodflowtothelimbsandorgans.Thiscancausepainandorgandamage.

∙Thepainfromsicklecellanemiacanbeacuteorchronic,butacutepainismorecommon.Acutepainissuddenandcanrangefrommildtoverysevere.Thepainusuallylastsfromhourstoaslongasaweekormore.

∙Manypeoplewhohavesicklecellanemiaalsohavechronicpain,especiallyintheirbones.Chronicpainoftenlastsforweeksormonthsandcanbehardtobearandmentallydraining.Chronicpainmaylimityourdailyactivities.

∙Almostallpeoplewhohavesicklecellanemiahavepainfulcrisesatsomepointintheirlives.Somehavethesecriseslessthanonceayear.Othersmayhavecrisesonceamonthormore.Repeatedcrisescandamagethebones,kidneys,lungs,eyes,heart,andliver.Thistypeofdamagehappensmoreofteninadultsthaninchildren.

∙Manyfactorscanplayaroleinsicklecellcrises.Often,morethanonefactorisinvolvedandtheexactcauseisn'tknown.

∙Youcancontrolsomefactors.Forexample,theriskofasicklecellcrisisincreasesifyou'redehydrated（yourbodydoesn'thaveenoughfluids）.Drinkingplentyoffluidscanlowertheriskofapainfulcrisis.

∙Youcan'tcontrolotherfactors,suchasinfections.

∙Painfulcrisesaretheleadingcauseofemergencyroomvisitsandhospitalstaysforpeoplewhohavesicklecellanemia.

Investigations

∙Bloodcount.ThelevelofHbisintherange6–8g/dLwithahighreticulocytecount（10–20%）.

∙Bloodfilmscanshowfeaturesofhyposplenismandsickling.

∙Sicklesolubilitytest.AmixtureofHbSinareducingsolutionsuchassodiumdithionitegivesaturbidappearancebecauseofprecipitationofHbS,whereasnormalHbgivesaclearsolution.AnumberofcommercialkitssuchasSickledexareavailableforrapidscreeningforthepresenceofHbS,forexamplebeforesurgeryinappropriateethnicgroupsandintheA&Edepartment.

∙Hbelectrophoresisisalwaysneededtoconfirmthediagnosis.ThereisnoHbA,80–95%HbSSand2–20%HbF.

∙Theparentsoftheaffectedchildwillshowfeaturesofsicklecelltrait.

WhatAreThalassemias?

∙Thalassemiasareinheritedblooddisorders."Inherited"meansthatthedisorderispassedfromparentstochildrenthroughgenes.

∙Thalassemiascausethebodytomakefewerhealthyredbloodcellsandlesshemoglobinthannormal.Hemoglobinisaniron-richproteininredbloodcells.Itcarriesoxygentoallpartsofthebody.Hemoglobinalsocarriescarbondioxidefromthebodytothelungs,whereit'sexhaled.

∙Peoplewhohavethalassemiascanhavemildorsevereanemia.Anemiaiscausedbyalowerthannormalnumberofredbloodcellsornotenoughhemoglobinintheredbloodcells.

WhatCausesThalassemias?

∙Yourbodymakesthreetypesofbloodcells:

redbloodcells,whitebloodcells,andplatelets.Redbloodcellscontainhemoglobin,aniron-richproteinthatcarriesoxygenfromyourlungstoallpartsofyourbody.Hemoglobinalsocarriescarbondioxidefromyourbodytoyourlungs,whereit'sexhaled.

∙Hemoglobinhastwokindsofproteinchains:

alphaglobinandbetaglobin.Ifyourbodydoesn'tmakeenoughoftheseproteinchainsorthey'reabnormal,redbloodcellswon'tformcorrectlyorcarryenoughoxygen.Yourbodywon'tworkwellifyourredbloodcellsdon'tmakeenoughhealthyhemoglobin.

∙Genescontrolhowthebodymakeshemoglobinproteinchains.Whenthesegenesaremissingoraltered,thalassemiasoccur.

∙Thalassemiasareinheriteddisorders—thatis,they'repassedfromparentstochildrenthroughgenes.Peoplewhoinheritfaultyhemoglobingenesfromoneparentbutnormalgenesfromtheotherarecalledcarriers.Carriersoftenhavenosignsofillnessotherthanmildanemia.However,theycanpassthefaultygenesontotheirchildren.

∙Peoplewhohavemoderatetosevereformsofthalassemiahaveinheritedfaultygenesfrombothparents.

WhatAretheSignsandSymptomsofThalassemias?

Alackofoxygeninthebloodstreamcausesthesignsandsymptomsofthalassemias.Thelackofoxygenoccursbecausethebodydoesn'tmakeenoughhealthyredbloodcellsandhemoglobin.Theseverityofsymptomsdependsontheseverityofthedisorder.

NoSymptoms

Alphathalassemiasilentcarriersgenerallyhavenosignsorsymptomsofthedisorder.Thelackofalphaglobinproteinissominorthatthebody'shemoglobinworksnormally.

MildAnemia

∙Peoplewhohavealphaorbetathalassemiatraitcanhavemildanemia.However,manypeoplewhohavethesetypesofthalassemiahavenosignsorsymptoms.

∙Mildanemiacanmakeyoufeeltired.Mildanemiacausedbyalphathalassemiatraitmightbemistakenforiron-deficiencyanemia.

MildtoModerateAnemiaandOtherSignsandSymptoms

∙Peoplewhohavebetathalassemiaintermediahavemildtomoderateanemia.Theyalsomayhaveotherhealthproblems,suchas:

∙Slowedgrowthanddelayedpuberty.Anemiacanslowdownachild'sgrowthanddevelopment.

∙Boneproblems.Thalassemiamaycausebonemarrowtoexpand.Bonemarrowisthespongysubstanceinsidebonesthatmakesbloodcells.Whenbonemarrowexpands,thebonesbecomewiderthannormal.Theymaybecomebrittleandbreakeasily.

∙Anenlargedspleen.Thespleenisanorganthathelpsyourbodyfightinfectionandremoveunwantedmaterial.Whenapersonhasthalassemia,thespleenhastoworkveryhard.Asaresult,thespleenbecomeslargerthannormal.Thismakesanemiaworse.Ifthespleenbecomestoolarge,itmustberemoved.

SevereAnemiaandOtherSignsandSymptoms

PeoplewhohavehemoglobinHdiseaseorbetathalassemiamajor（alsocalledCooley'sanemia）haveseverethalassemia.Signsandsymptomsusuallyoccurwithinthefirst2yearsoflife.Theymayincludesevereanemiaandotherhealthproblems,suchas:

∙Apaleandlistlessappearance

∙Poorappetite

∙Darkurine（asignthatredbloodcellsarebreakingdown）

∙Slowedgrowthanddelayedpuberty

∙Jaundice（ayellowishcoloroftheskinorwhitesoftheeyes）

∙Anenlargedspleen,liver,orheart

∙Boneproblems（especiallywithbonesintheface）

Diagnosis

Doctorsdiagnosethalassemiasusing bloodtests,includingacompletebloodcount（CBC）andspecialhemoglobintests.

∙ACBCmeasurestheamountofhemoglobinandthedifferentkindsofbloodcells,suchasredbloodcells,inasampleofblood.Peoplewhohavethalassemiashavefewerhealthyredbloodcellsandlesshemoglobinthannormalintheirblood.Peoplewhohavealphaorbetathalassemiatraitmayhaveredbloodcellsthataresmallerthannormal.

∙Hemoglobintestsmeasurethetypesofhemoglobininabloodsample.Peoplewhohavethalassemiashaveproblemswiththealphaorbetaglobinproteinchainsofhemoglobin.

（B）Excessivebloodlossanemia

Types&itscauses:

（i）Acutebloodlossanemiaoccurswhenalargeamountofbloodislostoverashortperiodoftime,whichcanhappenifsomeonehasaseriousaccidentorinjury.

（ii）Losingalittlebloodoveralongperiodoftimealsomightleadtochronicbloodlossanemia.Thiscanhappeningirlswhohaveheavymenstrualperiods,especiallyiftheydon'tgetenoughironintheirdiets.

Sign&symptoms:

∙Headache

∙Dizziness

∙Weakness

∙Shortnessofbreath

∙Tachycardia

∙Coldhandsorfeet

∙Paleoryellowskin

∙Black,tarry,orbloodystools*

Diagnosis:

Completebloodcount

（C）Irondeficiencyanemia

Atypeofbloodlossanemia.

Ironisanimportantbuildingblockforredbloodcells.Whenyourbodydoesnothaveenoughiron,itwillmakefewerredbloodcellsorredbloodcellsthataretoosmall.Thisiscalledirondefi