After doing a lot of online searches about thyroid conditions, do you think you might have hypothyroidism? Did you go to your doctor and ask to have your thyroid checked, only to be told that there is nothing wrong?
Unfortunately, the majority of the medical profession is trained to perform only one test, thinking that a TSH test (Thyroid Stimulating Hormone) is all that is required. Nothing could be further from the truth.
You can’t find what you don’t look for. There are many tests needed to thoroughly evaluate a thyroid condition like hypothyroidism, because there are many things that can go wrong with thyroid function. Today we will discuss the Essential Thyroid Panel, which is a good place to start looking for the approximately 30 different things that can cause your thyroid to function poorly.
Tip: For a complete evaluation there are a number of other tests you should have done, including: Iodine Loading Test, Iron Study, and Cortisol Testing.
As critical as these thyroid tests are, they do little good unless properly interpreted. Various ranges exist, based on the organization making the recommendations, and the type of range, pathological or functional. Since the majority of thyroid problems are ones of function rather than disease, the functional ranges are narrower and will detect imbalances at an earlier phase, before they progress to a disease state. If you suspect you have hypothyroidism, you’ll want to go to a doctor who understands what tests to run and how to interpret them.
Let’s learn a little about each of the 9 tests on the Comprehensive Thyroid Panel and what the results mean to you.
- Thyroid Stimulating Hormone (TSH) This is the most common test performed. TSH is a hormone released by the brain to stimulate the production of T4 thyroid hormone (called thyroxine) in the thyroid gland. There is supposed to be a feedback mechanism that controls the relationship between TSH and T4, so the higher the T4, the lower the TSH. For many reasons this does not function properly, so doctors trained in Functional Medicine place much less importance on TSH than does your family doctor. TSH is often elevated in more severe hypothyroid conditions, but can easily be normal or even low in less severe functional hypothyroidism. A high or low TSH only tells you that something is wrong, not why it is wrong. Read about a the trouble with relying solely on TSH here.
- Total Thyroxine (TT4) This is the major hormone produced by the thyroid gland. Over 99% of the total amount of any hormone is attached to a carrier molecule, and is inactive. Only the very small amount of unattached hormone can exert an effect. Measuring the Total T4 tells us how well the thyroid gland is producing thyroid hormone overall, but not how much of the most active thyroid hormone there is.
- Free Thyroxine (FT4) This test measures the small amount of free or unbound T4 in the blood. However free T4 itself has very little biological activity compared to Free T3, the most metabolically active thyroid hormone.
- Total Triiodothyronine (TT3) Like TT4, TT3 is a measure of both bound and free T3 hormone, again with over 99% of T3 being inactive because it is bound. A significant cause of hypothyroidism is the failure to convert T4 into T3 which happens in the liver, kidneys, and GI tract. Things like a selenium deficiency or too much of the hormone cortisol (the stress hormone) can cause this to happen, so when we see a normal TT4 and a low TT3, we know you aren’t converting T4 to T3.
- Free Triiodothyronine (FT3) FT3 is the major active thyroid hormone, with 5- 10 times the activity of Free T4. It binds to receptors sites on every cell of the body, where it acts to stimulate metabolism and increase energy production. If you are functionally hypothyroid, you will generally see levels below the functional range.
- Reverse T3 (rT3) This hormone is the mirror image of FT3. Like a mirror image, it does exactly the opposite of FT3. This hormone is almost totally ignored by the medical profession, and many doctors aren’t even aware of its existence; therefore it is rarely tested. Regardless of the ignorance of rT3, it is present for a reason. It is produced when the body is under severe stress, such as major surgery, trauma, infection or chronic stress from any reason. FT3 acts like a metabolic throttle. rT3 acts like a metabolic brake, reducing resting metabolism and preserving the body’s energy to fight the stress.
- T3 Uptake (T3U) This test is an indirect measure of the level of how many of the thyroid carrier molecules are in the blood. The more carrier proteins there are, the more T3 and T4 that can bind to them, reducing the amount of free or active hormones that can perform their function.
- Thyroid Peroxidase Antibodies (TPO-Ab) The body can produce antibodies against itself, called autoantibodies. They cause autoimmunity; in this case Hashimoto’s Autoimmune Thyroiditis. They damage thyroid cells, eventually leading to chronic inflammation or thyroiditis and hypothyroidism.
- Thyroglobulin Antibodies (TG-Ab) These autoantibodies can also be produced, damaging another part of the thyroid gland, leading to Hashimoto’s.