Hyperthyroidism is defined as any condition in which there is too much hormone produced in the thyroid gland. The most common cause is Graves’ Disease, which tends to run in families, and affects more commonly younger women. Another cause of hyperthyroidism is the presence of thyroid nodules that grow and increase activity (toxic nodular goiter). Currently, there are three types of treatment for hyperthyroidism: antithyroid medications (ATD), surgery and radioactive iodine. A physician will recommend one treatment over another, taking into account factors such as the age of the patient, pregnancy status, other illnesses and also physician/patient preference.
Antithyroid medications are very useful in both the long term treatment of hyperthyroidism as well as in the short term to prepare a patient for surgery or radioactive iodine therapy. Indeed, ATDs are the preferred therapy during pregnancy. In the US, there are two ATD available for use: propylthiouracil (PTU) and methimazole (MMI). In Europe, carbimazole (CMZ) is also an option (this drug is converted to MMI in the body). In general, PTU is used only during pregnancy or if there is an adverse reaction to MMI or CMZ. While generally well tolerated, all ATDs have been reported to cause adverse side effects such as agranulocytosis and birth defects and, rarely, liver failure.
Untreated or inadequately treated hyperthyroidism during pregnancy may poorly affect the mother and the developing baby, so treatment of hyperthyroidism in pregnancy is always recommended. The goal of this study was determine the frequency of side effects of ATDs in a large segment of the Danish population of child-bearing age.
THE FULL ARTICLE TITLE:
Andersen SL et al. Antithyroid drug side effects in the population and in pregnancy. J Clin Endocrinol Metab. January 27, 2016
SUMMARY OF THE STUDY
The Danish Medical Birth Register database, including ~2.3 million parents of babies born in Denmark between 1973 and 2008. This database was matched with data from the Danish National Prescription Register, which provided information regarding ATD use. The Danish Hospital Register was accessed for information regarding outcomes (liver failure, agranulocytosis and birth defects).