T3 / Triiodothyronine
T3 is short for triiodothyronine, and T3 is the thyroid active hormone at the cellular level, delivering oxygen and energy to cells, tissues and glands throughout the body.
While the thyroid gland produces both T4 and T3, the T4 is inactive. In order to be of use to the body, the T4 is converted to T3. Increasingly, however, experts are identifying that nutritional deficiencies, toxins, and a variety of other physiological factors may prevent the body from accomplishing that conversion process effectively, leaving some patients deficient in this most important thyroid hormone.
A Free T3 blood test - along with clinical signs and symptoms of hypothyroidism -- may help identify whether a patient has normal levels of available T3, or may benefit from T3 treatment. Some integrative physicians believe that adequate thyroid replacement will result in Free T3 levels in the middle to upper half of the laboratory reference range.
In late 2009, a Danish study, reported on in the prestigious European Journal of Endocrinology, studied the thyroid symptoms impact of a levothyroxine-only therapy, versus levothyroxine plus T3 (in this case, a dosage of 20 micrograms of T3 daily was used.) Tests for quality of life and depression were done at the start of the study, and again after 12-week treatment periods. During each of the two 12-weeks periods, subjects were either given levothyroxine plus T3, or levothyroxine plus a placebo, and then switched for the next 12-week period. Participants were "blind" in that they were not aware whether they were taking active T3 or placebo.
The quality of life and psychological factors evaluated included, among other factors: general health, social functioning, mental health, vitality, sensitivity, depression, and anxiety. The study showed that among the patients, most of whom were women, 49% of the patients preferred the combination treatment, and only 15% preferred levothyroxine-only treatment.
Researchers and endocrinologists have been going back and forth for more than a decade about the value of T3, but based on their own practical experience with patients, and on the growing body of research evidence, holistic and integrative hormone experts are increasingly adding supplemental T3 as a solution to help optimize thyroid treatment for some patients. They add T3 in one of several ways:
- Adding T3 to levothyroxine treatment, via the addition of the prescription synthetic T3 drug Cytomel, or generic liothyronine (synthetic T3)
- Adding synthetic T3 via prescription compounded time-released /sustained-release T3 in addition to levothyroxine
- Adding a dosage of a natural desiccated thyroid, such as the prescription drugs Nature-Throid, Armour Thyroid, or generic natural thyroid (the U.S. manufacturer is Acella) to a levothyroxine treatment
- Switching patients to a natural desiccated thyroid-only treatment approach
- Putting a patient on a T3 only therapy (this is fairly uncommon.)
It's important to note, however, that because T3 is the active hormone, it can have an over-stimulatory effect on heart rate and pulse in some people, especially those with a history of heart disease, the elderly, and those with heart irregularities like mitral valve prolapse. T3-savvy physicians evaluate the safety of T3 as compared to the potential benefits on a case-by-case basis.
Even in those patients who do not have any heart or age-related issues that may make T3 problematic, some patients are simply more sensitive to T3. The heart is very sensitive to thyroid hormone in general, and for some people, even low doses of Cytomel or generic liothyronine can cause a rise in pulse, or heart palpitations.
For those patients, physicians often recommend the time-released/ sustained-release/ slow-release form of T3, available by prescription from compounding pharmacies.
Some integrative physicians, in fact, believe that the slow-release T3 is actually the optimal form for supplemental T3, as it more closely resembles the body's own conversion to and release of T3, and because the slow-release form is less likely to cause any side effects.
Natural Desiccated Thyroid
Some practitioners have found that certain patients simply do best on natural desiccated thyroid. This drug -- known as porcine thyroid -- or sometimes as "natural thyroid" or "pig thyroid" -- is manufactured from the dried thyroid gland of pigs. The drugs in this category include Armour Thyroid, Nature-throid, and Erfa Thyroid, and a generic natural desiccated thyroid is produced in the U.S. by Acella.
Natural desiccated thyroid has been in use for more than a century. Many integrative hormone experts believe that these drugs, which provide T4, T3, T2, T1, and other thyroid hormones and nutritional elements, more closely resemble human thyroid hormone than the synthetic drugs, and report that their patients feel better on them. Some patients find that they feel best on natural thyroid drugs, or on synthetic drugs plus some natural thyroid.
Keep in mind that the conventional endocrinologists do not view natural thyroid drugs favorably. They claim that these drugs are out of date, not "consistent," and many simply will not prescribe them. If you want this type of medication, you may work with a licensed holistic or alternative physician. (Note that over-the-counter glandular thyroid supplements are not prescription thyroid medication.)