Thyroid hormone is a metabolic hormone secreted by the thyroid gland that regulates temperature, metabolism and cerebral function. It contributes to energy levels and temperature regulation and body warmth. It increases fat breakdown, resulting in weight loss as well as lower cholesterol. It protects against cardiovascular disease and improves cerebral metabolism. It helps to prevent cognitive and memory impairment. Thyroid hormone is probably the safest and most beneficial cholesterol- lowering agent, yet it is infrequently used for this! More than any other hormone, the thyroid hormone is most responsible for improvement in energy and reducing fatigue.
We often get calls from patients whose primary care physicians have told them their thyroid is too low or too high. Because this is confusing, let us try to give you a better understanding.
The thyroid gland produces a hormone called T4. The number 4 indicates it has four iodine molecules. The body produces an enzyme that removes an iodine molecule and converts the T4 hormone into T3, which is the active form of the thyroid hormone. What is free and circulating in the system, available for the body to use, is the Free T3. It is the Free T3 that has the effect on energy, metabolism, and all thyroid functions.
The most common thyroid measurement is the TSH or Thyroid Stimulating Hormone, which stimulates the thyroid gland to produce thyroid hormone. This is a gauge that is the opposite of your thyroid production. If the body senses there is enough thyroid present, the TSH will be low. Conversely, if the body senses there isn’t enough thyroid, the TSH goes up, trying to stimulate the thyroid gland to make more thyroid. Here is part of the confusion. If you doctor says your thyroid is low, do they mean the TSH is low, which indicates that your actual thyroid is high? Or do they mean that your actual thyroid is low, in which case the TSH would be high?
A second point of confusion, not well understood by your physicians: If your thyroid gland is producing T4 or you are taking thyroid in the form of T4 (most commonly Synthroid or levothyroxine), the TSH will respond to the presence of T4 and most probably below or at a number of which your physician is comfortable. HOWEVER, if the T4 is not converting into T3, the TSH will not reflect this. And if the T4 is not converting into T3, you might have all the symptoms of not having an adequate amount of thyroid since it is the T3 that is the gas in the tank. The only way to assess the Free T3 is to measure it.
Most physicians do not measure Free T3 but only measure TSH. However, as seen above, it is not a full picture of your thyroid function. Most doctors are taught to treat this TSH number and not necessarily listen to how the patient feels (most patients feel better when Free T3 is optimal).
When you supplement with Armour Thyroid or compounded desiccated thyroid, it contains both T4 and T3 in a bioidentical form. The T3 gives you the energy early in the cycle while the T4 is converting into T3 for energy mid and late cycle (the cycle is typically about 7-8 hours). If we measure your Free T3 around 4-5 hours after you take your thyroid, we see how well your body is converting the T4 into T3. It is this measurement of Free T3 that is the most reflective of your thyroid levels.
Typically, when your Free T3 is optimal – close to the high end of a normal range – we will see that the TSH will be very low. This is what concerns your physicians. However, if your Free T3 is good and you feel well, without symptoms of too much thyroid (ie: heart palpitations, nervousness), your dose is usually fine, or as we prefer to say, optimal.
HOWEVER, because this difference of opinion seems to anger some primary care physicians, when your doctors test your TSH and advise you that your thyroid dose needs lowering, and we are advised of this, we will be lowering your thyroid dose to please your physicians. Appeasing them will spare you any confusion, but might result in a return of low thyroid symptoms.