Management of Hyperthyroidism in Pregnant Women

First-Line Treatment Approach

The American Academy of Family Physicians recommends propylthiouracil (PTU) as the preferred antithyroid medication during the first trimester of pregnancy due to lower risk of congenital abnormalities compared to methimazole 1, 2
The goal of treatment is to maintain free T4 or free thyroxine index (FTI) in the high-normal range using the lowest possible thioamide dosage 1
Regular monitoring of thyroid function every 2-4 weeks is recommended to adjust medication dosage appropriately 1

Monitor free T4 or FTI every 2-4 weeks to guide dosage adjustments 1
Beta-blockers (e.g., propranolol) can be temporarily used to manage symptoms like tremors and palpitations until thioamide therapy reduces thyroid hormone levels 1
Check TSH level every trimester to ensure stable thyroid function 3
Monitor for side effects of thioamides, particularly agranulocytosis (presenting with sore throat and fever) 1

Thyroidectomy should be reserved for women who do not respond to thioamide therapy 1
If the patient develops intolerance to antithyroid drugs (such as agranulocytosis or severe hepatotoxicity), thyroidectomy may be considered 1, 4
If surgery is necessary, the second trimester is the preferred timing 3

Radioactive iodine (I-131) is absolutely contraindicated during pregnancy as it can cause fetal thyroid ablation 1
Inadequately treated hyperthyroidism increases risks of preeclampsia, preterm delivery, heart failure, and possibly miscarriage 5
Fetal and neonatal risks include low birth weight and potential thyroid dysfunction 5

The newborn's physician should be informed about maternal Graves' disease due to the risk of neonatal thyroid dysfunction 1

The American Academy of Family Physicians recommends propylthiouracil (PTU) as the preferred antithyroid medication during the first trimester, while methimazole (carbimazole) is preferred in the second and third trimesters 6

Untreated or inadequately treated hyperthyroidism during pregnancy can lead to serious maternal and fetal complications, including preterm birth and stillbirth 6

Biochemical hyperthyroidism associated with hyperemesis gravidarum rarely requires treatment unless other clinical signs of hyperthyroidism are present, according to the American Academy of Family Physicians 7
Routine thyroid testing is not recommended unless other hyperthyroid signs exist, as stated by the American Academy of Family Physicians 7
Thyroid storm is a medical emergency that presents with fever, disproportionate tachycardia, altered mental status, vomiting, diarrhea, and cardiac arrhythmia, and requires immediate treatment without delay for laboratory confirmation, as recommended by the American Academy of Family Physicians 7
Treatment for thyroid storm includes PTU or methimazole, potassium/sodium iodide solutions, dexamethasone, phenobarbital, and supportive care, as suggested by the American Academy of Family Physicians 7
Avoid delivery during thyroid storm unless absolutely necessary, as advised by the American Academy of Family Physicians 7
Women must wait four months after I-131 treatment before breastfeeding, as recommended by the American Academy of Family Physicians 7