The Wise Use of Thyroid Hormone T3 in Treating Depression

Cytomel or the T3 form of thyroid hormone has a long use in psychiatry for the treatment of depression.

In fact, while many endocrinologists and family doctors today prefer to use T4 aka Synthroid monotherapy only for the treatment of hypothyroidism, psychiatrists are one of the specialties who are actually familiar with the value of adding Cytomel/T3 in the treatment of depression, specially in the types of depression where treatment with anti-depressants alone is insufficient.

Why Use Thyroid Hormone to Treat Depression?
Thyroid hormone is a hormone that affects almost every tissue in the body, but moreso the brain. We already know that thyroid hormone is essential during fetal development in pregnancy. A deficiency of thyroid hormone during pregnancy can cause mental development retardation. This is why pregnant women with hypothyroidism are more closely monitored and given more thyroid medication during pregnancy.  Thyroid hormone is so important that the brain uses a different set of genes to convert T4 into T3. Recall, T4 is the more abundant but less active form of thyroid hormone in the body, while T3 is the more active but less available form of hormone produced by the thyroid gland.

Many of the symptoms associated with hypothyroidism or low thyroid hormones levels are similar to the symptoms of depression. They include fatigue, slow thinking, low moods.

It is also worthwhile to note that a significant percent of persons with major depression have hypothyroidism or subclinical hypothyroidism.

You can now see that there is a big overlap between hypothyroidism and depression.


What is the evidence for using Cytomel to treat depression?
A summary of the literature and evidence is discussed in the journal Current Psychiatry. Here's an overview of some of the evidence:

• A meta-analysis has found that adding Cytomel to tricyclic antidepressants can speed up or accelerate the time it takes for depression symptoms to lift. One study found a reduction in depression symptoms (using Hamilton scale) of 50% by an average of 11 days with T3 augmentation vs. an average of 22 days with tricyclic anti-depressants alone.  Another study also showed that women seemed to respond more favorably with Cytomel augmentation with response evident by day 3 for some. 

• Another study found similar results-that Cytomel augmentation with SSRI's is also effective. SSRIs are the most commonly prescribed antidepressants these days with brand names such as Prozac, Lexapro, Zoloft, Paxil. 

• Another impressive study called STAR-D showed that Cytomel augmentation was effective in treating depression among patients who've already tried two other anti-depressants that didn't work on their own. Another point to consider is that the other medication they tried, lithium, was also shown to improve depression among persons who did not improve on other anti-depressants but that Cytomel showed fewer side effects than Lithium, making Cytomel the more rational/safer option. 

How can this be useful for me?

There are a few important take-aways here:

• Do not take a diagnosis of depression at face value. Always ask your doctor if they can also test if you are hypothyroid.  This is a good differential to make. If your TSH is perfect (what "perfect" is partly a matter of opinion, for me, it means it should be at least 2.5 or lower.)  If your thyroid labs are normal but between 2.5 and 4.5, then thyroid hormones should be considered if "conventional" treatments for depression such as medication, counseling, psychotherapy, cognitive behavioral therapy do not work or do not work well enough. 

• Cytomel aka T3 aka the more active form of thyroid hormone seems to be the specific type of thyroid hormone to take to treat depression symptoms. Synthroid does not seem to have the same efficacy.  Armour or Nature-Throid have both forms of T3 and T3, so they are better than Synthroid alone. However, because Armour and Nature-Throid are derived from natural sources, there may be a higher variation in their T3 content, so consider  Cytomel. 

• There are nuances in using Cytomel to augment the treatment of depression. In my practice, most patients will improve with a low dose addition of Cytomel in the morning. However, I have found that some patients will need a compounded time-release version of Cytomel to get the optimum results.