What are the most common causes of hyperthyroidism during pregnancy?
Overall, the most common cause (80-85%) of maternal hyperthyroidism during pregnancy is Graves’ disease (see Graves’ Disease brochure) and occurs in 1 in 1500 pregnant patients. The diagnosis of hyperthyroidism can be somewhat difficult, as 123I thyroid scanning is contraindicated during pregnancy due to the small amount of radioactivity, which can be concentrated by the baby’s thyroid. Consequently, diagnosis is based on a careful history, physical exam and laboratory testing.
