suprised doctor looking at a pile of medications, which are causing confusing thyroid blood work

Thyroid lab tests are commonly run. Oftentimes, the lab results make sense and treatment is straightforward. However, there are a lot of cases where the lab results don’t correlate with your symptoms, or the lab results contradict each other.

Click here to learn more about how thyroid test results can be confusing.

This article focuses one cause: drugs affecting thyroid hormone physiology.

The Effects of Pharmaceutical Agents on Thyroid Function

With so much of the population taking prescription medications, and growing numbers taking multiple medications, this is of the most common causes of confusing thyroid lab work.

As you’ll see, pharmaceutical agents can affect the thyroid function tests in multiple ways.

Some Drugs Affect Thyroid Hormone Secretion [1]

  • Iodide
  • Amiodarone
  • Lithium
  • TKIs
  • Immune modulators

Some Drugs Affect TSH Secretion [1]

  • Dopamine agonists
  • Glucocorticoids
  • Somatostatin analogues
  • Rexinoids
  • Metformin

Some Drugs affect conversion of T4 into the more active T3 [1]

  • Propylthiouracil
  • Glucocorticoids
  • Propranolol
  • Iodinated contrast media or iodine-containing supplements
  • Amiodarone


If you’ve got thyroid results back, and they don’t make sense, make sure your doctor is considering the effects your medications may have on your thyroid health. This is important to avoid unnecessary or inappropriate treatment. In some cases, we treat the thyroid anyway, but it's valuable knowing the reason why your thyroid hormones are off.


Interested in learning more?

Read on in our series of articles on Thyroid Health!

About the Author - Dr. Johann de Chickera

man facing camera

Dr. Johann is a fully licensed Naturopathic Doctor. His approach emphasizes the importance of living a healthy lifestyle and improving one’s health naturally. Dr. Johann obtained a Doctor of Naturopathy at the Canadian College of Naturopathic Medicine (CCNM). Education at CCNM is a vigorous four years, with a curriculum involving biomedical sciences, physical diagnosis, clinical nutrition, traditional Chinese medicine and acupuncture, botanical (herbal) medicine, physical medicine, homeopathy and lifestyle management.

While Dr. Johann has a general practice, he focuses on fertility, hormonal imbalances, gut health, and autoimmune disease.

To book in please call us at (519) 442-2206 or click here.

Leave a Comment