pengobatan tirotoxicosis.doc

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Treating thyrotoxicosis in pregnant or

potentially pregnant womenThe risk to the fetus is very low

M J ODoherty, Consultant physicianDepartment of Nuclear Medicine, Guys and t Thomas !ospital, "ondon #$ %#! mail'

m(odoherty)umds(ac(uk*

+ Mc#lhatton, Consultant teratolo-ist

! " Thomas, Consultant physician

National Teratolo-y .nformation ervice, e-ional Dru- and Therapeutics Centre, /olfson 0nit of

Clinical +harmacolo-y, Newcastle N#1 2!!

3uthor information 4Copyri-ht and "icense information 4

Copyri-ht5 $666, 7ritish Medical Journal

This article has 8een cited 8yother articles in +MC(

Thyroto9icosis affects up to :(1; of pre-nant women($.f left untreated it is associated with

increased fetal mortality and mor8idity(1Treatment is with antithyroid dru-s such as

propylthiouracil or car8imauences of maternal antithyroid treatment, and sometimes conflictin- or

inappropriate advice is -iven( /omen e9posed to antithyroid dru-s or radioiodine immediately

8efore or in early pre-nancy need accurate and timely information when decidin- whether to

proceed with the pre-nancy(

There are two concerns a8out antithyroid dru-s for thyroto9icosis' that the dru-s cause

hypothyroidism in the fetus and that they have terato-enic effects( These dru-s cross the placenta

and can sometimes cause fetal hypothyroidism and -oitre(?The fetal thyroid 8e-ins to develop at @A

B weeks -estation, with follicles and colloid production at $:A$1 weeks( 3dverse effects on fetal

thyroid function are thus unlikely unless treatment 8e-ins after $: weeks -estation(2.n two studies

in which antithyroid therapy was used in moderate doses maternal and fetal outcomes were

satisfactory, re-ardless of which antithyroid dru- was used(1,@Close monitorin- of thyroid function,

rou-hly once a month, is important 8ecause the need for antithyroid treatment often declines

throu-h pre-nancy, and in the midAtrimester it may occasionally 8e discontinued.

ecent studies have not su--ested that antithyroid treatment has adverse conse>uences on thyroid

siuent physical or intellectual development, as occurs in con-enital

hypothyroidism(BThere is e>uivocal evidence su--estin- that placental transfer of propylthiouracil

may 8e less than that of car8ima


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women with untreated thyroto9icosis &?@:E B;* than in those receivin- methimauences, includin- mental retardation(

The second concern is the potential -enetic effect resultin- from parental -onadal e9posureE several

studies have shown chromosomal dama-e after radioiodine( !owever, the increased risk of -enetic

a8normalities arisin- from such e9posure &:(::?;* is far less than the spontaneous risk of -enetic

a8normalities &:(;*( tudies in Japanese atomic 8om8 survivors and in the offsprin- of those

treated with hi-h doses of radioiodine for thyroid cancer have shown little evidence of

-enoto9icity($$Nevertheless, an interval of at least four months is normally advised 8etween

maternal radioiodine therapy and conception and some also apply this interval to a prospective

father(

The risk from radioiodine of herita8le disease or cancer has 8een estimated at $ in $1 ::: per mGyto the fetus($1.n early pre-nancy, althou-h the risk of cancer induction is not uotient points per mGy, which is unlikely to 8e clinically important($1

.f, however, the radioiodine was taken up 8y the fetal thyroid &after a8out $:A$1 weeks* then the

destruction of the fetal thyroid and su8se>uent hypothyroidism would result in a -reater loss of

mental function than that due to the direct radiation effect($2

The final area of concern relates to 8reast feedin- since all antithyroid dru-s, and iodine, are

e9creted in 8reast milk( The proportion of the adult dose consumed 8y a 8reastfed 8a8y has 8een

calculated to 8e a8out :(:%; for propylthiouracil, :(@; for car8ima


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2( 7alla8io M, Nicolini 0, Jowett T, ui< de #lvira MC, #kins +, odeck C!( Maturation of

thyroid function in normal human foetuses( Clin #ndocrinol( $66E?$'@B@H@%$( I+u8Med

@( /in- D3, Millar "K, Koonin-s ++, Montoro MN, Mestman J!( 3 comparison of

propylthiouracil versus methima


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treatment is withdrawn 2 weeks prior to delivery after which normal doses may 8e resumed(

Often hyperthyroidism due to GravesQ disease improves spontaneously across pre-nancy, so a

smaller dose of antithyroid dru- may 8e re>uired(

adioAiodine is contraindicated and pre-nancy should 8e avoided for at least 2 months

followin- receipt of .A$?$(

pengobatan tirotoxicosis.doc

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