This is a brief note about the use of T3 (the active from of thyroid hormone in the body) in the treatment of depression. Thyroid augmentation, though usually well tolerated, has the potential for serious side effects and should only be done in conjunction with a professional licensed to prescribe it.
Low levels of thyroid hormone are associated with depression, and many clinicians check a TSH level (a very sensitive screening test for low thyroid, known as hypothyroidism) as part of the assessment of symptoms of depression.
It is less widely known that even if a person has normal levels of thyroid, they may benefit from taking T3 as a supplement or augmentation agent along with their antidepressant.
T3 has primarily been studied in combination with tricyclic antidepressants (such as imipramine, doxepin and nortriptyline). However, it has also been combined with an SSRI (selective serotonin reuptake inhibitor), such as in the STAR-D studies. In one of the STAR-D studies, when citalopram (a SSRI) was ineffective on it’s own for major depression, either T3 or Lithium was added to citalopram. T3 and lithium were equally effective as an add-on agent for decreasing symptoms of depression; however, T3 was better tolerated.
In general it appears to be more helpful for women than men, and very well tolerated. In my experience it works quickly, but in the STAR-D study the mean time to becoming well took 6 weeks, and for some this did not occur until week 14. So be patient with it.
The usual starting dose is 25 micrograms (not milligrams, the typical unit of dosing in psychiatry), though sometimes it is better to start with just 12.5 mcg. This dose is usually continued for about 2 weeks before assessing benefits and side effects. The maximum dose is 50 mcg/d. Don’t be surprised if you find that it helps and you start wondering if an even higher dose would work better. Don’t increase it on your own. After a month a TSH level should be checked to make sure that you are not getting too much T3.
T3 is generally quite safe and easy to tolerate, but too much is associated with atrial fibrillation and osteoporosis. Symptoms of hyperthyroidism, a condition in which the body is making too much thyroid hormone (or is taking too much) include sweating, loose stools, anxiety, rapid heart rate and heat intolerance.
T should be taken on an empty stomach to improve absorption. Antacids, zinc and iron supplements can decrease absorption.
I have frequently discussed using T3 as an augmentation agent. Both I and my patients have been struck by it’s lack of side effects and the improvement in energy and mood that they experienced. One of it’s most attractive features as an add-on agent is it’s ability to improve energy, and for some people, to decrease appetite, or at least not increase appetite (which is a side effect of many augmentation agents). It has sometimes been hard to put the brakes on over enthusiastic patients who have suffered from depression, decreased motivation, lack of enthusiasm and no pleasure for a long time. It is easy to understand the reasoning: “if 50mcgs helps, 75 or a 100 would be fantastic”. Don’t do it. Check a TSH level, and respect that though T3 can help, it is a potent substance and must be used appropriately.
For more information refer to the following articles:
1. Augmenting antidepressants with triiodothyronine: An underutilized strategy:T3 augmentation can improve depressive symptoms in patients without subclinical hypothyroidism
Current Psychiatry Vol. 10, No. 07 / July 2011 Daniel Gih, MD
2. T3 Augmentation in Major Depressive Disorder: Safety Considerations
Jackson Tyler Dempsey Practical Psychiatry 