An overactive thyroid gland, also referred to as hyperthyroidism or Graves’ disease, is an important health concern. Thyroid disease is serious as the thyroid controls the body's metabolic processes. According to the LLLI BREASTFEEDING ANSWER BOOK (BAB), any breastfeeding mother with thyroid disease should be under the care of a doctor who is supportive of her desire to breastfeed.
Diagnosis of an overactive thyroid can usually be based on the mother's symptoms as well as a simple blood test. On occasion, radioactive testing is used to diagnose thyroid problems. If radioactive testing is recommended, the mother can ask her physician if the test could be postponed or another, non-radioactive test, be substituted.
If the radioactive test is used, temporary weaning is recommended. "The length of time the mother needs to suspend breastfeeding will depend on the type and dosage of radioactive materials used for the test" (BAB). Radioactivity of breastmilk declines over time, and frequent milk expression will help the mother eliminate the radioactivity from her body more quickly. This milk must be discarded and not fed to the baby. (Frequent milk expression will not hasten the elimination of other drugs from breastmilk.) For pumping information see LLLI FAQs about pumping.
Contact a La Leche League Leader for the most up-do-date information about the time period needed to sufficiently clear radioactivity from breastmilk.
Some medications for overactive thyroid are not concentrated in human milk and result in minimal doses to the breastfed baby. If a mother is taking thyroid suppressants, she will need to tell her baby's doctor so the baby can be monitored for thyroid levels. Weaning is usually not necessary. If a doctor insists on weaning, the mother is encouraged to seek a second opinion before weaning. When temporary weaning is recommended, it is important to be sure the risks and benefits have been fully evaluated. If you have questions about the medications you are taking, contact a La Leche League Leader.
If radioactive compounds are used to treat an overactive thyroid, temporary weaning is necessary. The mother will need to pump and discard the milk during this time. Before a mother resumes breastfeeding, her milk must be checked for radioactivity. Your local LLL Leader will be able to share more information and offer support.