If you have hypothyroidism or Hashimoto's thyroiditis you've probably done a lot of blood draws and tests. It's pretty routine to regularly check thyroid levels to see if medication and treatment is working and keeping your hormones in healthy ranges.
Thyroid disease can affect and be affected by other body systems like the heart, adrenals, digestive and immune systems and testing them in addition to the thyroid can be helpful for guiding treatment. Many doctors don't order testing beyond the thyroid. If you aren't feeling better and are wondering if there might be other issues going on keep reading to learn more about additional testing that could shed some light on health issues that are often related to hypothyroidism.
What Tests Are in a Thyroid Panel?
thyroid stimulating hormone (TSH)
triiodothyronine (T3)
thyroxine (T4)
reverse T3 (rT3)
Most doctors will test thyroid function with thyroid stimulating hormone (TSH) and thyroxine (T4) but there are other tests that can give a broader picture of thyroid function. There's another thyroid hormone called triiodothyronine (T3) that is the active hormone that helps regulate many of our body systems including our brain, heart, immune, skin, and reproductive systems. Some doctors don't test for T3, but I think it can be helpful to see how well the body is converting inactive T4 to active T3 and you want to make sure there are adequate amounts of T3. If the conversion isn't going well there are ways to promote it with nutrients to help you feel better.
Reverse T3 (rT3) is another one that's not usually tested but can be helpful to see if active T3 is being converted into inactive rT3. Reverse T3 acts like a safeguard to prevent too much stimulation by T3. The body will convert both T3 and T4 into rT3 if there is too much.
Reverse T3 can be helpful because T3 and T4 may appear in the normal range but if your body is converting thyroid hormone to rT3, then you also may not feel better. There are many reasons for the body to make rT3 such as abnormal blood sugar, infections, chronic stress, and hormonal imbalance and looking into these causes can help to provide a more complete treatment plan.
Testing for Autoimmune Hypothyroidism
anti-thyroid peroxidase (anti-TPO)
anti-thyroglobulin (anti-Tg)
Hypothyroidism can be caused by an autoimmune process where the immune system will attack the thyroid, thyroid hormone receptors or enzymes that make thyroid hormones. In this case it's known as Hashimoto's thyroiditis or autoimmune hypothyroidism. There are tests that can be done to find out whether an autoimmune reaction is occurring. It can be important to know this information because there are other treatment considerations if there is autoimmunity going on such as addressing inflammation in the digestive system.
The markers you look for in autoimmunity are antibodies. Antibodies are made when our immune cells encounter a foreign target like a virus or bacteria. They help to fight the invader and stick around for the rest of our lives in case we encounter that invader again. Usually our body is good at knowing the difference between what is foreign and what is ourself, but when it gets confused and attacks our own tissues that's when an autoimmune reaction can occur. Our body can make antibodies against our own tissues, including the thyroid.
In the case of Hashimoto's thyroiditis, there are two antibodies to look for in the blood: anti-thyroid peroxidase (anti-TPO) and anti-thyroglobulin (anti-Tg). Thyroid peroxidase is an enzyme that helps to convert T4 to T3. If it's being attacked, you're not going to get much active T3 and can have symptoms of hypothyroidism. Thyroglobulin is the source of both T4 and T3 so antibodies against it will decrease the production of both thyroid hormones.
Other Tests to Consider in Hypothyroidism
EBV panel
Food allergies
Celiac disease
Adrenal profile or AM cortisol
Like everything in our body, the thyroid is linked to the function of other body systems. A dysfunction in one system can affect the function of another. The immune system, adrenals, and digestive system are a few notable systems to check when treating thyroid disease.
Epstein-Barr virus (EBV) is a virus that most of us have been exposed to whether it made us sick or not. It causes mononucleosis aka "mono" or the "kissing disease" in the teens and early adulthood. Mono causes extreme fatigue, flu-like symptoms, muscle and joint aches, depression and sometimes can result in an enlarged spleen. Like other viruses, this virus can stay dormant in our body or reactivate and cause an autoimmune reaction. In the case of Hashimoto's thyroiditis, EBV "hides out" in the thyroid gland and the body mistakenly attacks our cells because it thinks it's the virus. Testing for EBV is by blood test, initially running a panel to see if the virus is reactivated and then checking one value periodically to see if levels are decreasing as treatment progresses.
The digestive system plays a role in the start of autoimmunity. You may have heard of "leaky gut" where the intestines is permeable to proteins getting through and getting into the blood stream. The proteins that get through are seen as foreign and can trigger an attack on other tissues including the thyroid. Testing for food allergies and Celiac disease can help to identify foods that are damaging the digestive system. Taking these foods out of the diet can help the gut to heal and calm the immune system preventing further attacks on the body's tissues.
Cortisol from the adrenal glands can have a direct effect on thyroid hormones and affect lab results. Cortisol can suppress thyroid hormone production and push T3 towards rT3. It can also impact the immune system and allow latent infections, like EBV, to reactivate. Testing is pretty easy and can be done with a blood test in the morning when it's expected to be high. Saliva testing 3-4 times per day can be another way to test and gives a nice picture of how cortisol changes for you throughout the day. If the cortisol rhythm is off there are many ways to support the adrenals with rest, adaptogens, diet, nutrients and stress management techniques.
Summary
If you have hypothyroidism you're probably familiar with routine thyroid testing for TSH and T4. There are other tests that may help to give a more complete picture of how your thyroid is functioning. These tests include T3 and reverse T3. Thyroid disease can be caused by autoimmunity and antibody testing for anti-TPO and anti-Tg are two markers that may be elevated in Hashimoto's thyroiditis. The thyroid affects many other body systems and sometimes testing those can help to alleviate symptoms and heal the whole body. This is when EBV, Celiac disease, food allergy panel and testing adrenal function can be useful. If you've been treating hypothyroidism and are not feeling better you may want to get these tests done to help guide treatment and help you feel better.
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Dr. Jamie
This website is not intended for the purpose of providing medical advice. All information, content, and material of this website is for informational purposes only and are not intended to serve as a substitute for the consultation, diagnosis, and/or medical treatment of a qualified physician or healthcare provider.
Resources
Romm, Aviva. “Hashimoto's Root Causes.” Aviva Romm MD, 30 Dec. 2017, avivaromm.com/top-hypothyroid-triggers/.
Romm, Aviva. “Hypothyroid Testing: 6 Labs To Ask For.” Aviva Romm MD, 17 Dec. 2018, avivaromm.com/hypothyroid-testing-need-know/.
Wentz, Izabella, et al. “6 Different Hashimoto's Root Causes - Dr. Izabella Wentz.” DR. IZABELLA WENTZ, PHARM D, 23 Nov. 2018, thyroidpharmacist.com/articles/6-different-hashimotos-root-causes/.
Zaidi, Sarfraz. Hypothyroidism and Hashimoto's Thyroiditis: a Groundbreaking, Scientific and Practical Treatment Approach. IComet Press, 2014.