The magnitude of increased Levothyroxine dose during pregnancy in patients on thyroid-stimulating hormone (TSH) suppression treatment after total thyroidectomy for papillary carcinoma

Management of Hypothyroidism and Hypothyroxinemia in Pregnancy

OBJECTIVE

To review the diagnosis and management of hypothyroidism in pregnancy, preconception, and the postpartum period.

METHODS

Literature review of English-language papers published between 1982 and 2022, focusing on the most recent literature.

RESULTS

During pregnancy, thyroid function laboratory tests need to be interpreted with regard to gestational age. Overt hypothyroidism, regardless of the TSH level, should always be promptly treated when it is diagnosed preconception or during pregnancy or lactation. Most women with preexisting treated hypothyroidism will require an increase in levothyroxine dosing to maintain euthyroidism during gestation. levothyroxine-treated pregnant patients need close monitoring with serum thyroid stimulating hormone (TSH) to avoid or- or under treatment. There is no consensus about whether to initiate levothyroxine in women with mild forms of gestational thyroid hypofunction. However, in light of current evidence it is reasonable to treat subclinically hypothyroid women with levothyroxine, particularly if the TSH is >10 mIU/L or the thyroperoxidase antibody is positive. Women who are not treated need to be followed to ensure that treatment is initiated promptly if thyroid failure progresses. Additional studies are needed to better understand the effects of the initiation of levothyroxine in early gestation in subclinically hypothyroid and hypothyroxinemic women and to determine optimal strategies for thyroid function screening in preconception and pregnancy.

CONCLUSION

The diagnosis and management of hypothyroidism in the peripregnancy period present specific challenges. In making management decisions, it is essential to weigh the risks and benefits of treatments not just for the mother but also for the fetus.