From the Guidelines
Transient hyperthyroidism in pregnancy is a temporary condition that typically resolves on its own by the second trimester without requiring specific treatment. This condition is primarily caused by high levels of human chorionic gonadotropin (hCG), which can stimulate the thyroid gland to produce excess thyroid hormones, as seen in the context of thyroid disease in pregnancy 1. Symptoms may include mild heat intolerance, increased heart rate, and weight loss despite normal appetite. Most cases are mild and do not require medication. However, if symptoms are severe, beta-blockers like propranolol may be used short-term for symptom relief.
It is essential to differentiate transient hyperthyroidism from other thyroid disorders like Graves' disease, which may require more aggressive management during pregnancy, as Graves' disease is responsible for 95 percent of hyperthyroidism cases in pregnancy 1. Regular monitoring of thyroid function is important, with TSH and free T4 tests recommended every 4-6 weeks. While transient hyperthyroidism usually resolves spontaneously, it's crucial to monitor the condition to prevent potential complications, such as severe preeclampsia, preterm delivery, heart failure, and possibly miscarriage, which can occur if hyperthyroidism is not treated adequately 1.
Key considerations in managing transient hyperthyroidism in pregnancy include:
- Monitoring thyroid function regularly
- Differentiating the condition from other thyroid disorders like Graves' disease
- Avoiding antithyroid medications due to potential risks to the fetus
- Using beta-blockers short-term for symptom relief if necessary
- Being aware of the potential complications if the condition is left unchecked, such as affecting fetal growth and maternal health 1.
From the Research
Definition and Causes of Transient Hyperthyroidism in Pregnancy
- Transient hyperthyroidism in pregnancy is a condition characterized by temporary elevated levels of thyroid hormones, often caused by high circulating concentrations of human chorionic gonadotropin (hCG) [ 2 , 3 ].
- This condition is typically reported in women with hyperemesis gravidarum, a condition marked by severe nausea and vomiting during pregnancy [ 2 ].
- Transient hyperthyroidism of hyperemesis gravidarum is defined as severe nausea and vomiting, dehydration, ketonuria, and weight loss of more than 5% by 6 to 9 weeks of pregnancy, with thyroid tests in the hyperthyroid range [ 3 ].
Diagnosis and Management
- The diagnosis of transient hyperthyroidism in pregnancy is based on the presence of hyperthyroidism symptoms and elevated thyroid hormone levels, which normalize with the resolution of vomiting [ 3 ].
- Antithyroid drug (ATD) therapy is not indicated for transient hyperthyroidism of hyperemesis gravidarum, as the condition is self-limiting and resolves with the improvement of symptoms [ 3 ].
- However, ATD treatment may be necessary for other forms of hyperthyroidism in pregnancy, such as Graves' disease, to prevent adverse outcomes for the mother and the fetus [ 2 , 4 ].
Relationship to Other Pregnancy-Related Conditions
- Transient hyperthyroidism in pregnancy can be associated with other conditions, such as gestational trophoblastic disease and postpartum thyroiditis [ 2 , 5 ].
- Hyperemesis gravidarum, a condition characterized by severe nausea and vomiting, can also be associated with transient hyperthyroidism [ 3 ].