放射性碘療法 (英文)

RadioiodineTherapy

I-123(123I)-------diagnosticapplicationI-124(124I)-------PETscanI-125(125I)-------diagnosticandtherapeuticapplication

I-131(131I)RadioactiveIodine……

I-125(125I)In1942

HertzandRobertsHamiltonandJ.H.LawrencehyperthyroidismIn1943

Seidlinetal.thyroidcarcinomaI-131(131I)BenignThyroidDiseases

Hyperthyroidism(Graves’disease)ToxicNodularGoiterNontoxicNodularGoiter

MalignantThyroidDisease

DifferentiateThyroidCaner(DTC)papillarythyroidcancerfollicularthyroidcancermixtureofpapillaryandfollicularthyroidcancerIodine-131TherapyforHyperthyroidismSIGNSANDSYMPTOMSSkin:IncreasedSweatingandheatintolerance,onycholysis,hyperpigmentation,pruritusandthinningofthehair.Eyes:Stareandlidlag,exophtalmosifgravesdiseaseCardiac:Palpitations,exertionaldyspnea,anginal-likechestpain,tachycardia,atrialfibrillation,CHFGI:Weightloss,diarrheaNeuro-psych:Anxiety,restlessness,irritability,emotionallability,psychosis,agitation,anddepressionMetabolic/Endocrine:

Hyperglycemia,lowserumtotalandhigh-densitylipoprotein(HDL)cholesterolGRAVES’DISEASESignsandsymptomsofhyperthyroidismExopthalmos,proptosis,lidlag,orbitaledema

DiffusegoiterTSHreceptorantibodiesIncreasedRAIuptakeGraves’ophthalmopathyDiffuseGoiterAntithyroidDrug(ATDs)

methimazolepropylthiouracilSurgeryIodine-131TherapyforhyperthyroidismTheATDsinhibitthyroidhormonebiosynthesis.Theyareusefuleitherasaprimaryformoftherapyortolowerthyroidhormonelevelsbeforeradioactiveiodinetherapyorsurgery.Long-termATDtherapymayleadtoremissioninsomepatientswithGraves’disease.Thereisnoclear-cutstandardfordurationoftherapywithATDS,butwhenusedasprimarytherapy,theyareusuallygivenfor6monthsto2years,althoughalongerperiodofadministrationisacceptable.

ATDsAdversereactionstobothmethimazoleandpropythiouraciloccur,includingrash,arthralgiasorhepaticabnormalities.Themostseriousreactiontoeitherdrugisagranulocytosis,whichoccursinabout0.3%ofpatients.ATDsWhenapatientwithverylargegoiter,thyroidectomyisinfrequentlyrecommended.SurgeryPatientsmustbecautionedaboutpotentialcomplicationsofsurgery,includinghypoparathyroidismandinjurytotherecurrentlaryngealnerve.Radioactiveiodine(Iodine-131)isthemostcommonlyusedformoftreatmentintheUnitedStates.70%physicianwouldliketorecommendiodine-131forhyperthyroidisminasurveyin2011.Treatmentwithiodine-131doesnotcauseareductioninfertilityanddoesnotcausecancer,norhasitbeenshowntoproduceilleffectsinoffspringofthosesotreatedpriortopregnancy.Soitisverysafe.Iodine-131131IATDSurgeryUSA69%31%EUROPE22%77%<2%JAPAN11%88%choiceregion<1%Choicefora43

yearsoldwomanwithhyperthyroidism(ATA,In1999)Thyroidtissuecapableofproducingthyroidhormonewilltrapandorganifyiodine-131.Onceiodine-131hasbeentakenupbythethyroidtissue,The

β-radiationgivenbyiodine-131iseffectiveinirradiatingtheimmediatelocalregionoftissueinwhichtheiodine-131isconcentrated,sinceβ-radiationisabletotravelonlymillimetersintissue.Subsequenttoirradiation,celldeathoccursoveraperiodofweekstomonths.PrincipleTherapywithiodine-131iscontraindicatedduringpregnancyandinwomanwhoarebreast-feeding.Itsuseinindividualsundertheage20years,whilecontroversial,iscommon.ContraindicationLowiodinedietWithdrawATDsAradioactiveiodineuptaketest(RAIU)isusuallyperformedjustpriortotheadministrationofiodine-131todeterminetheappropriatedose.PreparationFixedmillicurieadministrationThefixeddoseamountvariesdependingpatient’sstatusfrom3-7mCi(111to259MBq)to10-15mCiforGraves’disease.AhighdoseregimenofradioactiveiodinetreatmentismoreeffectivethanthelowdoseoneDeliveredmicrocuriespergramDeliveredactivityof2.96–7.4MBq(80–200μCi)pergramofthyroidtissueisgenerallyappropriate.ThethyroidradiationdosedependsontheRAIUaswellasthebiologicalandeffectivehalf-lifeoftheradioiodineinthethyroidglandDosestrategiesFactorsinfluencethedoseofradiationdeliveredtothyroidby131I:1)Thedegreeofuptakeof131I(RAIU)

2)Thebulkoftissuetobedestroyed3)Thelengthofresidenceof131Iwithinthetissue4)Thedistributionof131Iwithinthetissue5)TheradiosensitivityoftheparticularcellsFormulasforthecalculationofactualadministeredactivityofradioiodineDoseof131I=weightofthyroid×dosewillbedeliveredforpergramofthyroidtissue÷RAIUElderlypatientsorindividualsatriskfordevelopingcardiaccomplicationsmaybepretreatedwithATDspriortoiodine-131therapy,especiallyifhyperthyroidismissevere,todepletetheglandofstoredhormone,therebyminimizingtheriskofexacerbationofhyperthyroidismduetoiodine-131inducedthyroiditis.

Insomepatients,ATDsmayberequiredforcontrolforseveralmonthsfollowingradioiodinetherapy.PreparationComplicationEarlycomplicationsExacerbationofHyperthyroidismThisisduetopostradiationthyrocytedestructionandthyroidhormonesreleaseRadioiodineandophthalmopathyRadioiodinetherapyisassociatedwiththeappearanceorexacerbationofophthalmopathymoreoftenthanantithyroiddrugtherapyorsurgeryRadioiodinetreatmentmayincreasetheinflammatoryprocessandexacerbatetheophthalmologicalsymptoms.LatecomplicationsThereisnoclearevidenceofincreasedrateofmalignancyorgeneticconsequencesinpatientstreatedwithradioiodineItisassumedthatradioiodinetreatmentleadstohypothyroidisminmostpatients.However,itcannotbeconsideredasasideeffectofsuchtherapy.OntheotherhandinductionofhypothyroidismisconsideredthegoaloftherapyPost-therapyhypothyroidismVariousstudieshaveshownthat20%to64%ofpatientsbecamehypothyroid1yearaftertreatmentandthatthesubsequentincidenceofhypothyroidismisapproximately3%to5%eachyearLatehypothyroidismwhichoccursatarelativelyfixedrateappearsindependentofdoseandmaybemorerelatedtothenaturalhistoryofthediseaseMeierDA,DworkinHJ,BenderJM.Therapyforhyperthyroidism.In:HenkinRE,BovaD,DilleheyGL,HalamaJR,KareshSM,WagnerRH,ZimmerAM,editors.NuclearMedicine.2nded.Philadelphia:MosbyElesvier;2006.p.1567-1575Patientsshouldbeseenat4-to6-weekintervalsforthefirst3monthsfollowingradioactiveiodinetherapy,andthenatintervalsastheclinicalsituationdictates.Hypothyroidismgenerallyensuesfollowingtreatmentwithinthefirst6to12monthsfollowingtherapy,butmayoccuratanytime.Therefore,atleastannualfollow-upisnecessaryforthoseindividualswhocontinuetobeeuthyroid.Continuing

care131I

therapyhalfayearlaterFT3,FT4,TSH131I

therapyhalfayearlaterFT3,FT4,TSHRadioiodinetherapyforDTCDTC(differentiatedthyroidcarcinoma)PapillarythyroidcarcinomaFollicularthyroidcarcinomaMixedpapillary-follicularthyroidcarcinoma

DTCcellscanconcentrateradioiodine,sowecantreatitwithradioiodinebyβ-radiationrays.PostsurgicalAblationFunctioningMetastasesPostsurgicalAblation1.Surgeryisseldomabletoeffectremovalofallofthefunctioningthyroidtissue,eveninthebesthands2.RadiationablationofaftersurgicalremovalofthethyroidisassociatedwithadecreasedriskofrecurrenceanddeathinpatientswithDTC131IdoseForlowriskpatients,30mCiisusuallythedoseforphysicians’choicesForhighriskpatients,100to200mCiusuallybeusedFunctioningMetastasesFunctioningmetastaseslesionsareusuallyfoundon:LungBrainBoneTherapeuticiodine-131dosesof5.55-7.4GBq(150-200mCi)areadministeredtoeradicatemetastaseslesionsofDTCIodine-131maybeadministeredupto5to10times,

Whole-bodyiodine-131scansinsearchofmetastasesaregenerallyrepeatedat6-moorannualintervals,followedbyrepeattherapydosesofiodine-131whenwarrantedFunctioningMetastasesInanycase,serumTSHlevelsshouldbeinexcessof30IU/Lafteranappropriateperiodofthyroidhormonewithdrawaltofacilitateuptakeofthetherapydoseof131IbythefunctioninglesionsExogenousTSHalsocanbeusedtosupplementendogenous