We wanted to share with you the most important thyroid markers that your doctor may need to be running on you to evaluate your thyroid hormone metabolism.
These markers will give you a much better sense of what is actually going on with your thyroid gland, your pituitary gland, adrenal glands and how well your hormones are being converted in the liver, kidneys and gut. These markers will also rule out the possibility of an autoimmune condition that is affecting your thyroid health.
Print out this information and arm yourself with information for your next doctor’s appointment. You may not need all of them, but it is good to be an informed patient. Do not be intimidated by the language and terms, we will explain them as we go.
Commonly Used Terms
TSH – The most common marker used to assess thyroid function and the most sensitive. This hormone is released by the pituitary when it gets the signal from the hypothalamus. TSH levels increase when T4 levels drop, and TSH decreases when T4 levels are elevated. Sometimes this is the only marker your doctor will order.
T4 – This is the most prevalent form of thyroid hormone made by the thyroid gland. Levels of T4 in the blood act as the feedback loop for the brain and signal it to stop producing TSH. The vast majority of it is bound to carrier proteins. It is considered metabolically inactive, and must be converted to its active form to be used by cells to regulate metabolism. Typically the only other marker tested other than TSH.
T3 – The active thyroid hormone. If it is not directly made in the thyroid gland, then conversion takes place in the liver, kidney, and GI tract. The majority of T3 is bound to carrier proteins. Once unbound, T3 acts directly on the cell nucleus to regulate the metabolism of that cell.
Free T4 – This is the unbound version of T4. This marker can be influenced by thyroid hormone replacement, chronic illness, as well as disorders that affect the amount of carrier proteins.
Free T3 – The unbound form of T3. This is the best marker to see what amount of active thyroid hormones are available for the cells. This can be affected by stress, thyroid disorders, and pregnancy.
Reverse T3 – This version of T3 is metabolically inactive. Reverse T3 is only typically produced in cases of extreme stress such as surgery or trauma. Chronic stress can also cause the production of Reverse T3, thereby masking the adrenal issue and looking like a dysfunctional thyroid.
T3 Uptake – This measures the number of sites for T3 to bind to for carrier proteins. These are the sites that allow T3 to be transported throughout the body to be used by cells that need it. This marker is influenced by sex hormones such as testosterone and estrogen.
Thyroxine-Binding Globulin (TBG) – This is the amount of proteins in the blood that carry thyroid hormones to the cells. This marker can be influenced by infections, liver dysfunction, HRT, birth control, steroids, prednisone, aspirin, and pregnancy.
TPO Antibodies – Most common marker elevated with autoimmune thyroid. 90% of thyroid issues are autoimmune related. This marker is rarely tested since there is no pharmaceutical drug to fix the problem, only lifestyle.
Anti-thyroglobulin Antibodies – Not as commonly elevated with an autoimmune thyroid condition. During thyroid cancer treatment, this marker is routinely evaluated.
Thyroid Stimulating Immunoglobulin – These antibodies are elevated with an autoimmune thyroid condition called Grave’s disease. This marker indicates a hyperthyroid state. This marker might only be required if your doctor is suspecting Grave’s Disease. This is an overly active thyroid condition cause by autoimmunity.
If you have a hard time getting these markers run by your healthcare provider, please contact us to discuss your case in more detail. We are devoted to serving those in need. You may not need all of these tests, but it is good to know that they are available for your doctor to evaluate.