Many common problems such as fatigue, depression and difficulty losing weight can be due to low thyroid, however, many people, especially women, are not getting the treatment that would be of great benefit. This is because severely low thyroid levels are often not picked up by the standard TSH, T4, and T3 testing, which is the only testing done about 90% of the time.
New studies indicate, however, that the ratio of active thyroid hormone, T3, to the T3 blocking hormone, reverse T3, must be determined to accurately determine an individual’s true thyroid levels. This can often reveal a problem of hypothyroidism even though the standard tests are normal. This test is rarely done, however, even though this is the most important determinate of thyroid function. Individuals on thyroid hormone also often receive improper doses, usually too low, when the TSH is used for dosing.
There is mounting evidence that hypothyroidism is present in the majority of and possibly all fatigued patients. The problem is that standard blood testing that consists of TSH, T4 and T3 does not detect it. Thus, many patients are erroneously told over and over that their thyroid levels are fine. TSH is secreted by the pituitary in the brain, telling the thyroid to secrete T4, which is not the active thyroid hormone. T4 must then be converted in the body to the active thyroid hormone T3. When T4 and T3 levels drop, the TSH should increase indicating hypothyroidism. This is the standard way to diagnose hypothyroidism. There are, however, many things that result in hypothyroidism but are not diagnosed using the standard TSH and T4 and T3 testing. This method misses thyroid problems with patients 90% of the time.