8 Things Every Thyroid Evaluation MUST Check For
By Dr. Jonathan Wright on 06/25/2009 (http://www.healthiertalk.com)
When patients come to the Tahoma Clinic with symptoms of weak thyroid function, we start by getting their complete medical history and doing a thorough physical exam. But we also run a complete set of blood tests. I stress the word “complete” because, unfortunately, many thyroid function tests leave out at one or more important markers. In order to get a full picture of your thyroid health, though, a comprehensive test should include the following eight measurements:
Thyroid stimulating hormone, or TSH. Made by the pituitary gland, this hormone stimulates the thyroid gland to make its hormones, which include T4, and T3, (and T2, and T1, too!) This hormone usually—but not always—rises if the thyroid gland isn’t responding to the usual degree of TSH stimulation.
Theoretically, if there’s enough active thyroid hormone TSH stays below a certain level. For this reason (and because it’s less expensive for insurance companies) many physicians—even a few endocrinologists—rely on the TSH evaluation alone to assess thyroid function. This only gives you a small fraction of the “big picture.”
Free T4, also known as thyroxine. (Technically speaking, thyroxine is made up of two tyrosine molecules bound to four iodide molecules.) Free T4 is generally considered the “storage and transportation” form of thyroid hormone, although it does have some activity of its own.
Free T3, or tri-iodothyronine. (The biochemical make-up of tri-iodothyronine consists of two tyrosine molecules bound to three iodide molecules.) Free T3 is the very metabolically active form of thyroid hormone.
Reverse T3, also known as reverse tri-iodothyronine or rT3. (Its biochemical composition also involves two tyrosine molecules bound to three iodide molecules, but they’re not in the same positions on the tyrosine molecules as free T3). As mentioned on page 1, rT3 is a reverse mirror image of free T3 that blocks free T3 from doing its job.
Total T4 and total T3. These are the same basic hormones in free T4 and free T3—thyroxine and tri-iodothyronine—but instead of being bound to iodide, in this instance, they’re bound to a large protein molecule called thyroglobulin, which researchers have found to completely de-activate any thyroid bound to it.
Thyroglobulin Antibodies (TGA), Thyroperoxidase Antibodies (TPO). When either or both of these antibodies are elevated, it indicates auto-immune thyroid disease. This situation is frequently (but not always) associated with gluten/gliadin sensitivity. Elevated TGA and/or TPO are another frequently missed cause of thyroid malfunction, missed because they’re often not tested.
There are also a number of other thyroid hormones which aren’t presently measured in any available thyroid tests: total T2, free T2, total T1, and free T1. The function of these hormones just hasn’t been adequately researched. In fact, T2 and T1 have been ignored and called useless, much as DHEA was for nearly two decades. However, evidence exists that T2 stimulates growth hormone in humans, as well as mitochondrial function, gene transcription, and enzymes. T1 likely has important functions, too, even if they aren’t yet well known. Hopefully, as more research is done, testing for these hormones will become available.
One more note, just to be clear: Even though elevated rT3 almost always indicates an accumulated excess of toxic metals, not everyone with excess toxic metals has an elevated rT3. Similarly, many hypothyroid individuals are hypothyroid for other reasons, and not because of toxic metals.