Thyroid hormone is responsible for modulating your metabolism, growth and other functions. The system for controlling the production of thyroid hormone begins in a small area of the brain called the hypothalamus. The hypothalamus produces a hormone called thyrotropin-releasing hormone (TRH) which travels down a dedicated pathway to the anterior pituitary gland, which is then stimulated to produce thyroid stimulating hormone (TSH). When TSH is released into the bloodstream, it stimulates the thyroid gland to produce tetraiodothyronine (T4) and triiodothyronine (T3). The ratio produced is 80% T4 and 20% T3.
T4 and T3 travel throughout the body. The major effects on the cell are seen with T3 as it performs the vital intracellular functions. Most of the T4 becomes active only as it is converted to T3 by removal of an iodine molecule. T4 has four iodine molecules and T3 has three.
My testing for thyroid function focuses on three tests: TSH, Free T4 and Free T3. Many physicians will only test the TSH and if it is in the normal range, they will tell the patient that they are normal. This ignores the fact that many patients will have a normal TSH but will be deficient in Free T4 and/or Free T3. I feel all three need to be tested in order to get a clearer picture of what is going on with the thyroid regulation.
I break down thyroid problems by whether there is an overproduction of thyroid hormone (hyperthyroidism) or underproduction (hypothyroidism) and whether it is subclinical (abnormal TSH without abnormal Free T4 and no symptoms) or clinical (symptoms and abnormal TSH or Free T4 or Free T3 values). The feedback system to balance production of thyroid hormone is dependent upon the hypothalamus sensing the correct amount of Free T4 in the bloodstream and altering the TRH levels to influence the TSH production up or down as needed.
Thyroid hormone is not only depending on the above hormones for regulation as the system requires iodine and several other minerals for efficient production including selenium, zinc, molybdenum, boron, copper, chromium, manganese and magnesium. There are several commercially-prepared supplements that contain these minerals because many people are not eating foods with sufficient amounts of these minerals.
In the case of iodine, as I previously noted in my last article, for 80 years or so, all salt was iodized and all bread and cereal products were fortified with iodine because the soil in North America does not contain enough iodine to supply our bodies’ requirement. This regulation was removed when thyroid disease was controlled and the food industry successfully lobbied about 10 years ago to remove it due to the cost. Because of that change, we are seeing a resurgence of thyroid disease due to lack of iodine in our diet.
As time goes on, the efficiency of conversion of T4 to T3 decreases and the symptoms of hypothyroidism may occur with a normal TSH and a low T3 level with a normal T4. This is because the feedback system does not take low Free T3 into account but it certainly may cause symptoms. That is why I feel it is necessary to check all three measurements rather than just the TSH.
The symptoms of hypothyroidism include: fatigue, swelling of the legs, cold intolerance, weight gain, depression, brain fog, muscle cramps and weakness, and a slow heart rate. The mainstay of treatment of hypothyroidism is supplying the required minerals and iodine to support production and replacement therapy with thyroid hormone.
Thyroid hormone is given by most physicians as T4 only or levothyroxine. The thought is that it will lower the elevated TSH seen in hypothyroidism and thereby correct the problem. This is not true in a lot of my patients. As noted, the conversion of T4 to T3 becomes less efficient with time and only giving T4 may not correct this lack of T3. I normally give natural thyroid hormone which contains T4 and T3 in ratios similar to the 80/20 % noted earlier. This ensures that an adequate amount of T3 is immediately available to the cells. The common forms of natural thyroid hormone include Armour Thyroid, NP Thyroid, Westthroid, and Naturethroid. These are all derived from pig thyroid because humans actually share similar thyroid physiology with pigs. If there are religious or dietary reasons to avoid the natural pig thyroid hormones, there are synthetic versions of T3 and T4 that can be combined as necessary. I find that the combination is much better at treating hypothyroidism with much happier patients.
Too much thyroid hormone production is known as hyperthyroidism. The symptoms associated with too much production are weight loss, heat intolerance, muscle weakness, tremors, palpitations, rapid heart rate, and insomnia. Hyperthyroidism is more difficult to treat and requires more testing to determine the cause and decide on the best treatment. However, lack of treatment for either hypo- or hyperthyroidism can lead to devastating consequences, including death.
The downside in giving everyone thyroid medication is that some people will become hyperthyroid from the treatment with thyroid hormone, called iatrogenic hyperthyroidism. This is avoidable in most cases. I believe in treating the patient, not just the piece of paper that might place the lab results in the “Normal” range. I have learned over the years that “Optimal” and what is in the normal range on the paper are not necessarily the same. Sometimes going from the bottom of the “Normal” range to the top of the “Normal” range may markedly improve the patients functioning, even though both are “Normal”. This may be the way to optimize outcomes in some people.
It is amazing that all of our bodily functions perform so well for so long. I give credit to our Creator for the temple He allows us to inhabit for the blink of an eye. I am looking forward to experiencing my immortal body in heaven where we won’t have any more disease, suffering or pain. In the meantime, I will do my best to help ease the suffering and pain where I can. I know that everything beyond my reach is within the cradle of His arms. I recommend drawing closer to Him every day. If you don’t have a church home, please find one. Please pray and read the bible daily.
– Dr. David Jayne, M.D.
Edited by Ann Jayne