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T3 Triiodothyronine Drugs Improve Quality of Life for Hypothyroidism

Research Finds Most Patients Feel Better with Addition of T3


Updated June 09, 2014

Mixed race pharmacist giving prescription to customer
Terry Vine/Blend Images/Getty Images
February 11, 1999 -- The February 11, 1999 issue of the New England Journal of Medicine reports on the results of research that found that "treatment with thyroxine plus triiodothyronine improved the quality of life for most [hypothyroid] patients."

The article is titled:

"Effects of Thyroxine as Compared with Thyroxine plus Triiodothyronine in Patients with Hypothyroidism"
by Robertas Bunevicius, Gintautas Kazanavicius, Rimas Zalinkevicius, Arthur J Prange, Jr. Research was conducted by the Institute of Endocrinology, Kaunas Medical University, Kaunas, Lithuania along with the Department of Psychiatry, School of Medicine, University of North Carolina, Chapel Hill.

How the study was conducted

Essentially, they took a group of 33 people who were hypothyroid, either due to autoimmune thyroid disease, or removal of their thyroids due to thyroid cancer. All the patients were studied for two five-week periods. During one five-week period, the patient received his or her regular dose of levothyroxine alone. (Levothyroxine is the generic name for the brand names such as Euthyrox, Levoxyl, Levothroid and Synthroid.) During the other five-week period, the patient received levothyroxine PLUS triiodothyronine (T3.) (Note: In the U.S., the brand name for T3 is "Cytomel." ) In the T4 plus T3 phase, 50 µg of the patient's typical levothyroxine dose was replaced by 12.5 µg of triiodothyronine (T3). A variety of blood, cognitive, mood and physical tests were conducted at various stages of the testing.


From the standpoint of physiological effects, the differences between pulse, blood pressure, reflexes and a variety of other functions for T4 alone, versus T4 plus T3, were very small. Blood pressure and cholesterol in fact dropped slightly on the T4 plus T3.

Where the results were dramatic were in mental functioning. Patients performed better on a variety of standard neuropsychological tasks on the T4 plus T3. Patients' psychological state also showed improvement on T4 plus T3.

At the end of the study, patients were asked whether they preferred the first or second treatments. 20 patients said they preferred the T4 plus T3 treatment, 11 had no preference either way, and only 2 preferred T4 only. The 20 patients who preferred T4 plus T3 reported that they had more energy, improved concentration, and just felt better overall.

The researchers determined that "treatment with thyroxine plus triiodothyronine improved the quality of life for most patients."

The researchers also recommended that the ideal thyroid hormone replacement program for someone without a thyroid gland, or whose thyroid gland is nearly non-functioning, would be "10 µg of triiodothyronine daily in sustained-release form. . . along with enough thyroxine to ensure euthyroidism."

Implications for Your Treatment

This study has major implications for people who don't feel well on their current thyroid hormone replacement.

If you are on standard levothyroxine only therapy, it's possible that, like the majority of study subjects, you too could feel better with the addition of a time-release T3 product in the recommended dosage ratio.

If you are on Armour Thyroid or Thyrolar, the current percentages of T3 in those drugs may be somewhat too high, compared to the recommended ratios described in this study. Optimal results may be obtained by modifying the treatment regimen to conform more specifically to the recommended ratio described in this article.

If you are on thyroid hormone replacement and don't feel well, I recommend that you notify your doctor right away about this research study, and get a copy of this article for yourself as well.

If you are going to share any information with your doctor, at the same time, you might also want to share a copy of a British Medical Journal article that suggests that values above TSH of 2 may not be "normal," but in fact represent abnormal levels indicative of a thyroid already in the process of failing.

You can order a copy by calling the New England Journal's Customer Service Department at 1-800-THE-NEJM

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