Povišana koncentracija TSH matere med nosečnostjo je povezana z zapleti med nosečnostjo in po njej ter z zastojem razvoja ploda in njegovih možganov. Nosečnice, ki so jim kirurško ali z radiojodom odstranili ščitnico, so glede koncentracije ščitničnih hormonov odvisne od vnosa L-tiroksina s tabletami. V literaturi je izredno malo podatkov o tem, za koliko naj povečamo odmerek L-tiroksina med nosečnostjo pri bolnicah z rakom ščitnice, ki so imele operacijo ščitnice in ablacijo ostanka ščitnice z radiojodom. V prospektivni študiji pri 36 bolnicah z rakom ščitnice, ki jemljejo L-tiroksin v zavornih odmerkih, smo ugotovili, da se lahko koncentracija TSH med nosečnostjo zelo spremeni. TSH je ostal zavrt samo v četrtini primerov. V tretjem trimesečju je bil pri bolnicah, ki so imele zavrt TSH, povprečni odmerek L-tiroksina 160 μg. Pri nekaterih bolnicah smo med nosečnostjo spremenili odmerek L-tiroksina, in sicer v povprečju za 31,5 μg. Vsem nosečnicam, ki jemljejo L-tiroksin, moramo čim prej po zanositvi določiti koncentracijo TSH in ščitničnih hormonov. Svetujemo, da med nosečnostjo koncentracijo hormonov določamo na 4 tedne, da lahko pravočasno spremenimo odmerek L-tiroksina in tako preprečimo porast koncentracije TSH, saj je lahko škodljiv za nosečnico in plod oz. otroka.Elevated maternal concentration of TSH during pregnancy is correlated with complications during and after pregnancy and impairment of development of fetus and its brain. Pregnant women in whom the thyroid was surgically removed or who had radioiodine ablation are, with regard to the thyroid hormone concentration, dependant on the input of L-thyroxine with tablets. There are very scarce data in the literature about how the suppression dose of L-thyroxine should be modified in the patients with thyroid carcinoma after total thyroidectomy and radioiodine ablation of the thyroid remnant. In our prospective study we found out that, in 36 pregnant patients with thyroid carcinoma who were on suppressive doses of L-thyroxine, the concentration of TSH could change vastly. The TSH concentration remained suppressed during pregnancy in only one quarter of the patients. In the patients with suppression during the third trimester, the mean dose of L-thyroxine was 160 μg. In those patients in whom the dose was changed, the mean change of dose was 31.5 μg. In all pregnant women, the concentration of TSH and thyroid hormones should be determined as soon as pregnancy is confirmed. We recommend that, during pregnancy, the concentration of TSH and thyroid hormones is determined every four weeks in all pregnant women who are on L-thyroxine in order to change the dose and prevent the increase of TSH concentration which might be detrimental for the pregnant woman and the fetus