The thyroid is the regulator of your metabolic rate, akin to the idle in your car. It adjusts its influence on your “peppiness” on a millisecond to millisecond basis. To properly test its functionality there are common tests available from a standard lab, Most frequently, if the thyroid is to be evaluated at all, it is done with only one lab test and that is the TSH. This Thyroid Stimulating Hormone (TSH) emanates from the brain (pituitary gland) and signals the thyroid to speed up or slow down.

Let us look at symptoms and tests to help evaluate the thyroid. Symptoms to note include sluggishness, easy weight gain, brittle nails, hair loss, dry skin and, at times, constipation, increased cholesterol readings and lower basal body temperatures all reflecting a slower metabolism.

The thyroid’s primary function in regulating the metabolism is to assemble two raw materials to make its hormone, thyroxine (T4). These two materials are the amino acid tyrosine and the mineral iodine…as in one Tyrosine matched with 4 iodine. This hormone then needs to drop one if its iodines to form the hormone of greatest function, T3. This occurs in the liver and kidneys with the help of the mineral selenium. On occasion this process can get shunted and form more of what’s called “reverse” T3 that undermines the production of the regular T3 that is essential for metabolic efficiency, or optimal “idle” position.

The body is extremely complex with all its inner workings. There are two major systems in the body that highly influence the efficiency of the thyroid. One, is the immune system. It can be misguided to produce anti-bodies to protect you against thyroid elements that it perceives as threatening to your well-being. The two anti-bodies that have been recognized and had tests developed for are the Thyro-PerOxidase Antibody (TPO Ab) and the Thyrogobulin Antibody (Tg Ab). These antibodies can interfere with the functioning of the thyroid and actually injure the gland permanently. This attack on the thyroid is sometimes labelled with a person’s name, Hashimoto’s Disease. It is what’s known as an auto-immune condition, or attack on one’s self.

Another system that interferes with the thyroid is the adrenal system. Stress can produce an overabundance of cortisol (an adrenal hormone like adrenalin). Cortisol can block the conversion of the thyroid hormone (T4) to its more functional form (T3).

Considerations that lead one to suspect thyroid dysfunction include symptomatology, family history and exposure to toxins, in particular radioactive toxins.

Tests that help identify the mechanisms of dysfunction include: TSH, fT4 (“free” T4), fT3, rT3 (“reverse” T3), TPO Ab, Tg Ab, and Cortisol. Of these, the one test that will most likely identify a dysfunction is the fT3. That is the messenger (hormone) that triggers metabolic activity throughout the body, like the idle in your car.

Dr. Miles practices Naturopathic Medicine alongside other holistic practitioners at the Catalina Clinic of Integrative Medicine in Catalina, Arizona. Visit

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