by ICANS Editorial Team
The thyroid is a lesser known gland that has a large impact on how you look, feel, and perform. A butterfly shaped gland located at the front of the neck, the thyroid releases hormones that regulate metabolic, impact energy levels, and affect cardiovascular function among other things.
Unfortunately, problems with thyroid function often go unnoticed or are misdiagnosed by doctors. One reason for all the confusion is that the thyroid releases multiple hormones and is involved in a complicated hormonal cascade. For example, the thyroid releases two thyroid hormones, T3 and T4, as well as a hormone involved bone building, calcitonin.
T3 and T4 are released in response to a cascade that starts with the hypothalamus in the brain. The hypothalamus releases Thyroid Releasing Hormone (TRH), which goes to the pituitary (also in the brain), where it binds with receptors and triggers the release of Thyroid Stimulating Hormone (TSH).
TSH goes to the thyroid to stimulate the release of T3 (the active form of thyroid hormone) and T4 (the inactive form of thyroid hormone). When T3 levels drop, T4 will be converted into T3 by the liver. Thyroid hormone is made from iodine, which means that sufficient iodine intake is also necessary for optimal thyroid hormone release. Additionally, certain enzymes called the deiodinase enzymes are necessary for conversion of T3 from T4.
As T3 and T4 levels go up, a negative feedback message goes to the pituitary and hypothalamus to reduce levels of TRH and TSH, thereby keeping levels of thyroid hormone in the ideal physiological range. With so many moving parts, you can see that a lot can go wrong with thyroid function. Therefore, it’s important to have a framework for assessing thyroid function.
We’ve developed a four-step approach to achieving optimal thyroid function that can be remembered with the simple acronym ACER:
A is for Amount: This refers to the need to test levels of a variety of different hormones: TSH, T3, and T4 are the bare minimum that should be measured. For a complete picture of thyroid function, you want to assess Total and Free T3 and T4, TSH, TPO, Reverse T3, and T3 uptake.
C is for Conversion: This refers to how well the liver is at converting T4 into T3. A variety of things can impair conversion, including elevated cortisol and estrogen levels. About 80 percent of thyroid hormone release is in the form of T4 and only 20 percent is T3, so you need to make sure the liver is performing this conversion efficiently.
E is for Expression. This refers to how well T3 is able to bind to a cell’s thyroid receptor. In order for T3 to bind to a cell receptor and produce a biological effect, vitamin A is necessary. However, many people have low vitamin A levels, especially if they have low gall bladder function. You can have normal T3 and T4 levels, but without vitamin A it can’t bind to the receptor and won’t be active.
R is for Ratio. This refers to the ratio between the amount of free T3 and reverse T3. Reverse T3 is an inactive form of T3, which is produced by the body as a way to conserve energy. Reverse T3 is incapable of delivering oxygen or energy to the cells, as T3 does. The body produces Reverse T3 in response to high cortisol and chronic stress, low ferritin, calorie restriction, and disease.