GLP-1 medications have been gaining a ton of popularity in recent news for their use in treating type 2 diabetes and obesity. The different types of GLP-1 medications include semaglutide (Wegovy, Ozempic, Rybelsus), dulaglutide (Trulicity), liraglutide (Saxenda) and the new GLP-1 and GIP dual agonist on the market: tirzepatide (Mounjaro). If you are taking one of these medications or have been researching these medications to add to your weight loss journey, you may have heard the warnings about the risk of thyroid cancer. The warning states that people with a history of medullary thyroid cancer or a family history of Multiple Endocrine Neoplasia Cancer Syndrome Type -2 (MEN-2) should avoid taking these medications.
But what does this mean for people with other thyroid disorders, like hyperthyroidism and hypothyroidism? Should they avoid taking GLP-1 medications too? In this post, we will review some of the different thyroid diseases and discuss how GLP-1 medications may or may not impact them.
Of all the various beautiful glands in the body, the thyroid plays a part in almost all functions in the body from head to toe. It is a small, butterfly-shaped gland in the neck, just below the Adam's apple. The thyroid gland produces two main iodine-containing hormones, triiodothyronine (T3) and thyroxine (T4), which play a critical role in regulating metabolism, growth, and development throughout the body. They affect almost every organ in the body and play a crucial role in regulating metabolism, including how fast the body burns calories, body temperature, heart rate, and blood pressure. They also affect growth and development, especially in the brain and bone. The pituitary gland regulates the production and release of thyroid hormones at the brain's base.
Thyroid disorders typically arise when there is an imbalance in the levels of these thyroid hormones. The levels of thyroid hormones can be too high, causing hyper-thyroidism, or they can be too low, causing hypo-thyroidism. The underlying cause of the increase or decrease in thyroid hormone levels can vary from person to person.
Hypothyroidism can be due to a decrease in the production of thyroid hormones, a decrease in the release of thyroid hormones, or the destruction of the thyroid gland by the immune system. Below are some different causes of hypothyroidism:
Hyperthyroidism can be due to an overall increase in the production or release of thyroid hormones. It can also be seen when the immune system attacks the thyroid gland, which eventually leads to hypothyroidism. Common causes of hyperthyroidism include:
Though there appears to be an increased risk for medullary thyroid cancer with GLP-1 medications based on animal studies, the risk of developing other thyroid disorders is unknown. In a meta-analysis published in 2022 aimed at evaluating the relationship between the use of GLP-1 medications and the occurrence of thyroid disorders like hyper and hypothyroidism, researchers saw no significant effect on these disorders (1). Ultimately, they concluded that there was no increased risk of these thyroid disorders when taking GLP-1 medications however, the findings need to be examined further since the overall incidence of these diseases is low.
For the most part, GLP-1 medications can still be used for patients who have hyperthyroidism or hypothyroidism. The weight loss benefits from taking a GLP-1 medication may actually assist with weight management for people with hypothyroidism!
The concern for the development of medullary thyroid cancer when taking GLP-1 medications is still ongoing. An observational study published in 2023 in Diabetes Care that looked to determine whether the use of GLP-1 medications was associated with an increased risk of thyroid cancer found that in 1-3 years of treatment, the risk for thyroid cancer was increased for those taking GLP-1 medications (2). A few things to note about this study is that there was no significant increase in risk for people after three years on these medications. Along with this, the researchers only looked for “thyroid cancer” in general. There are different types of thyroid cancer; the specific type concerning GLP-1 agonist medications is Medullary Thyroid Cancer. This cancer is also very rare, so it is still hard to say there is a genuine increased risk. Nonetheless, your provider may still ask you about a medical history of medullary thyroid cancer or a family history of MEN-2 before starting you on GLP-1 medications.
As always, you should discuss your risk for the development of thyroid cancer with your provider before beginning GLP-1 medications and determine if the benefits of taking the medication outway your specific risk level.
If you would like to learn more about GLP-1 medications or want to see if you might be eligible for medication-assisted weight loss, check out Mochi Health, where board-certified obesity medicine physicians can offer expertise in this realm!
Dr. Constantine Joseph Pella, MD
Boston University Medical Center