Jiraporn SriprapapornJiraporn Sriprapaporn,, MM..DD..Nuclear MedicineNuclear Medicine

RadiologyRadiologySiriraj HospitalSiriraj Hospital

RAI TREATMENTRAI TREATMENT FORFORTHYROID DISORDERSTHYROID DISORDERS

HYPERTHYROIDISMHYPERTHYROIDISMGravesGraves’’ diseasediseaseToxic adenomaToxic adenomaMultinodular toxic goiterMultinodular toxic goiter((PlummerPlummer’’s diseases disease))

THYROID CANCERTHYROID CANCERDTCDTC

Treatment of HyperthyroidismTreatment of Hyperthyroidism

Medical Medical

SurgicalSurgical

Radioactive iodineRadioactive iodine

Medical Treatment of Medical Treatment of HyperthyroidismHyperthyroidism

Titrate the antithyroid drug dose every 4 weeks until thyroid functions normalize. Some patients with Graves disease go into a remission after treatment for 12-18 months, and the drug can be discontinued. Notably, half of the patients who go into remission have a recurrence of hyperthyroidism within the following year. Nodular forms of hyperthyroidism (toxic MNG and toxic adenoma) are permanent conditions and will not go into remission.

eMeddicine.com

Radioactive Iodine TherapyRadioactive Iodine Therapy

Radioactive iodine therapyRadioactive iodine therapy[7][7] is is the most the most common treatment for hyperthyroidism in common treatment for hyperthyroidism in adults in the United Statesadults in the United States. . Although the effect is less rapid than it is Although the effect is less rapid than it is in in antithyroidantithyroid medication or medication or thyroidectomythyroidectomy, it is effective and safe and , it is effective and safe and does not require hospitalizationdoes not require hospitalization. .

eMeddicine.com

RAI Treatment RAI Treatment foforrHyperthyroidismHyperthyroidism

RAI is widely used for RAI is widely used for >> 4040--5050 yrsyrs..No evidence of increased risk to develop No evidence of increased risk to develop

malignanciesmalignanciesII--131131 solution solution

Less expensive than ILess expensive than I--131131 capsulecapsuleEasily to adjust the doseEasily to adjust the dose

No patient isolation is necessary but No patient isolation is necessary but precaution is likelyprecaution is likely..Need birth controlNeed birth control for women in reproductive for women in reproductive life during the course of RAI treatment life during the course of RAI treatment !!!!

RRAIAI Treatment Treatment ffor or HyperthyroidismHyperthyroidism::IndicationsIndications

Failed medicalFailed medical//surgical treatmentsurgical treatment--relapserelapseSerious Serious adverse effectsadverse effects of antithyroid drugsof antithyroid drugs::drug allergydrug allergy,, agranulocytosisagranulocytosisInconvenience for frequent contactInconvenience for frequent contactPoor compliance of medicationsPoor compliance of medicationsPoor socioeconomic problemsPoor socioeconomic problemsPresence of serious associated medical illness Presence of serious associated medical illness egeg.. heart failureheart failure

RAI Rx RAI Rx forfor HyperthyroidismHyperthyroidism::ContraindicationsContraindications

PregnantPregnantLactatingLactating

Precaution: Severe hyperthyroidism

II--131131 Dose CalculationDose CalculationDose Determination Dose Determination -- formula belowformula below

Gland size, % uptake, dose of IGland size, % uptake, dose of I--131 /gram 131 /gram thyroid tissuethyroid tissue

Other factorsOther factorsSeverity of hyperthyroidismSeverity of hyperthyroidism

Types of hyperthyroidism: nodular* Types of hyperthyroidism: nodular* vsvsdiffusediffuseOther clinical parametersOther clinical parameters

RAI Dose = [Thyroid mass (g) x 80-200 uCi/gm]/% uptake

RAI RxRAI Rx:: ProceduresProceduresStop antithyroid drugs for Stop antithyroid drugs for 55--77 daysdays2424 hrhr.. II--131131 uptakeuptakeII--131131 Rx dose according to calculationRx dose according to calculation..Combined medical Rx in severe thyrotoxic ptsCombined medical Rx in severe thyrotoxic pts..Peak result of RAI Rx needs about Peak result of RAI Rx needs about 33--44 monthsmonths..Long term FLong term F//UU,, monthly after monthly after 11st RAI Rx st RAI Rx &&reevaluate before reRxreevaluate before reRx..Repeat RAI RxRepeat RAI Rx:: usually usually 33--6 6 mo interval if still mo interval if still hyperhyper..Thyroid HThyroid H.. replacement if permanent replacement if permanent hypothyroidism is developedhypothyroidism is developed..

RAI Treatment for Thyroid Cancer: Indications

Differentiated thyroid carcinomaPapillary carcinoma*Mixed papillary-follicular carcinomaFollicular carcinoma(Hurthle’s cell carcinoma)

*EXCEPT: Occult tumors <1 cm without invasive properties or metastatic evidence

RAI Treatment RAI Treatment oof f Thyroid CancerThyroid Cancer

SURGERYSURGERYNearNear--total thyroidectomytotal thyroidectomy

RAI TREATMENTRAI TREATMENTHORMONAL TREATMENTHORMONAL TREATMENT

Suppressive dose of thyroid Suppressive dose of thyroid hormone hormone ((TT4)4)

LONGLONG--TERM FOLLOWTERM FOLLOW--UPUPCHEMOTHERAPY OR ERTCHEMOTHERAPY OR ERT##

Rai Treatment Rai Treatment ffor Dor DTCTC::ContraindicationsContraindications

PregnanPregnancycyBreast feedingBreast feeding

Also birth control for women in reproductive life during the course of RAI treatment !!

RAI Treatment for DTC

Ablative treatmentThyroid remnant remaining postop.% uptake > 0.5%Dose 30-100mCi

Treatment of recurrent or metastatictumors: Dose:150-200 mCi

Functioning tumors that take up radioiodineRising Tg but diagnostic dose could not reveal evidence of tumor*

Rationales Rationales ofof II--131131 AAblationblation

1. To destroy any residual microscopic disease.

2. To increase specificity of subsequent 131I scanning for detection of recurrent or metastatic disease by elimination of uptake by residual normal tissue; and

3. To improve the value of measurements of serum thyroglobulin as a serum marker derived only from malignant thyroid cells.

Sherma SI Lancet 2003

Benefits Benefits oof f II--131131 TherapyTherapy

Decreases local recurrenceDecreases local recurrence

Improves survival in patients following Improves survival in patients following local recurrencelocal recurrence

Improve Improve patientpatientss’’ conditionconditions with bone s with bone metastasmetastaseess

Mazzaferri EL Am J Med 1994;418-28

RAI TreatmentRAI Treatment::RegulationsRegulations

If If >> 3030 mCimCi :: PPatient isolation for a few atient isolation for a few days days ((usually usually 22--33 daysdays)) is necessaryis necessary,, ieie..ADMISSION is requiredADMISSION is required!!If If << 3030 mCimCi :: NNo isolation is requiredo isolation is required,,thus thus OPD casesOPD cases are OKare OK!!DD//C when retained radioactivity C when retained radioactivity << 3030mCi or dose ratemCi or dose rate << 55 mremmrem//hrhr

100100 mCi ImCi I--131131 TreatmentTreatment

Separate the patient for Separate the patient for 4040 hrhr

DayDay DistanceDistance TimeTimeDD11 11 ftft 2020 minminDD22 11 ftft 11 hrhrDD33 11 m m 1010 hrhr

Patient preparationPatient preparation:: withdraw Twithdraw T44 for for 44--66weeksweeks,, or Tor T33 for for 22 weeks before RAI Rxweeks before RAI RxLow iodineLow iodine--containing diet intake for containing diet intake for 11 WkWkOn admissionOn admission,, prepare sour candies or prepare sour candies or fruitsfruits,, etcetcAvoid radioactivity contamination to the Avoid radioactivity contamination to the body and the roombody and the roomFrequent voiding after Rx espFrequent voiding after Rx esp.. in the first in the first few daysfew days..

RAI Treatment RAI Treatment ffor Dor DTCTC: : TechniquesTechniques

RAI Treatment RAI Treatment ffor Dor DTC:TC:ComplicationsComplications

Early complicationsEarly complicationsAcute radiation sicknessAcute radiation sicknessAcute sialoadenitisAcute sialoadenitisRadiation thyroiditisRadiation thyroiditisPainPain,, hemorrhage hemorrhage && swelling in the swelling in the metastasesmetastasesTransient BM suppressionTransient BM suppression

Late complicationsLate complicationsMalignanciesMalignancies-- leukemia leukemia 2%2% vs vs 0.1%0.1%

FFollowollow--up of DTC Ptsup of DTC Pts..Clinical history Clinical history && physical examinationphysical examinationBlood TestsBlood Tests

Serum thyroid hormones levels Serum thyroid hormones levels ((TSH TSH 0.10.1--0.40.4 mIUmIU//LL))Tumor marker ieTumor marker ie.. Tg Tg ((NN << 1 1 ngng//mlml)) && TgAb TgAb ((NN << 2255 mIUmIU//LL))Calcium balanceCalcium balance,, CBCCBC

II--131131 TBSTBS at at 66 momo--11 yr post Rx until negativeyr post Rx until negative**((also other parameters are negativealso other parameters are negative))

Other investigationsOther investigations egeg.. CXRCXR--yearlyyearly,, TlTl--201,201, TcTc--9999m MIBI scanm MIBI scan,, CT scanCT scan,, MRIMRIRepeat RAI RxRepeat RAI Rx:: at least at least 66--1212 months intervalmonths interval