A healthy thyroid produces the following hormones: T4, T3, T2, T1 and calcitonin.  T4, a storage hormone and the most abundant, is meant to convert to T3, the most active hormone.  T3 is also made directly.

But there’s another substance produced by the thyroid called RT3, which means Reverse T3. It is also converted from T4. And it’s NORMAL to have RT3.

Why does my body produce RT3 (Reverse T3)?    Your body, especially the liver, can constantly be converting T4 to RT3 as a way to get rid of any unneeded T4. In any given day, it’s stated that 40% of T4 goes to T3 and 20% of T4 goes to Reverse T3.

But in any situation where your body needs to conserve energy and focus on something else, it will change the above percentages, changing the conversion of RT3 to 50% or more, and the T3 goes down, down. Examples are emotional, physical, or biological stress, such as being chronically or acutely sick (the flu, pneumonia, etc), after surgery, after a car accident or any acute injury, chronic stress causing high cortisol, being exposed to an extremely cold environment, diabetes, aging, or even being on drugs like beta blockers and amiodarone. But there’s another reason for thyroid patients. Read on.

Can I as a thyroid patient make too much RT3? Definitely yes.  We can get caught in a state of alarm, causing our body to increase RT3 in order to decrease cellular reception of T3.  And the lower your T3, the worse you feel, including a lowered body temperature, fatigue, anxiety, weight gain, hair loss, a diagnosis of fibromyalgia and more….all reported by patients and confirmed when they discovered they had an RT3 problem..

What specifically are the reasons I, as a thyroid patient, make too much RT3? On top of the chronic stresses of your life, there are three common physiological reasons patients have noted, with the first two related to your adrenals (low cortisol, high cortisol), and the third related to your iron levels. Even low B12 and other chronic inflammation and other health issues can cause it.

1. When biological stress is excessive, such as being on the inadequate treatment of T4-only or being held hostage to the lousy TSH lab test (both which keep you underdosed or hypo), your adrenal glands produce high amounts of cortisol to help you cope with ongoing hypothyroidism and lingering symptoms and conditions.  The excess cortisol inhibits the conversion of T4 to T3,  and instead produces even larger amounts of RT3, creating an RT3 problem.
2. When biological stress is ongoing, your adrenals will eventually become fatigued, dropping from high cortisol to a mix of high and low, or all low,  and those low levels put you into the problematic state of adrenal fatigue, which causes chronic anxiety, poor coping skills, paranoia, easy nausea, sensitivity to light or sounds, psychological issues, etc.  When you don’t make enough cortisol, thyroid hormones can pool high in your blood. So your body responds by converting the T4 to excess RT3.
3. When ferritin, aka storage iron, is low, as can be your serum iron and saturation (which is quite common in thyroid patients), your red blood cells become less plentiful, and carrying thyroid hormones via your blood becomes inadequate, causing thyroid hormones to pool in your blood. The body responds by producing excessive amounts of RT3 to clear out the excess T4.

***Note that you can have either an iron problem, or a cortisol problem, or BOTH. There are other reasons you have high RT3, such as the excess inflammation and more, but the above are quite common and worthy to explore first.

Can labwork help me discover this? What do I look for? First, you have room to be suspicious when your Free t4 is higher in the range for awhile, especially above 1.4, and your free T3 is lower. Even having a high Free T3 due to adrenal or iron problems (see below) can be the beginning of too much RT3. But doing the RT3 has given patients the best clue, especially looking at the ratio between it and the FT3.

With the RT3 labwork, you are not necessarily looking for a Reverse T3 result high in the range, though that in itself can be a good clue. Instead, you are looking for a problem in the ratio between the RT3 and the Free T3.  i.e dividing the Free T3 by the Reverse T3 (Free T3 ÷ RT3).  For healthy amounts of RT3, The ratio result should be 20 or larger. If lower, you may have a problem. Janie has noted that many patients without an excess RT3 issue have a result of 23 or 24.

One place patients gained good information about all the above was from Dr. Kent Holtorf, here.  If you scroll down on the former page, you’ll also see mention of a study done with elderly men and RT3. Additionally, in the study article titled “Reverse T3 is the best measurement of thyroid tissue levels” found in the 2005, volume 90 issue of The Journal of Clinical Endocrinology & Metabolism, it states that  “the T3/rT3 ratio is the most useful marker for tissue hypothyroidism and as a marker of diminished cel­lular functioning.”

If you use the total T3, you are looking for a ratio greater than 10. If lower, you have a problem.  Note that the unit of measurements for the RT3 and Free T3 are often different on your labwork and will need to be changed in order to be the same. Figuring out your ratio is here.

Can I order my own labwork for this, since I doubt my doctor will do this? To order your own labwork, go here.  HealthcheckUSA will give you a discount if you put in STTM10. Remember to order a free T3 at the same time for ratio comparison. All facilities can test your ferritin without a doctor’s prescription.

I hate math. How can I figure out my ratio? If you don’t feel very math-savvy, STTM has created a beta conversion method for you, here. It still has a few kinks in places we are trying to work out. So let Janie know if you discover one.

What do I do about excess RT3?  Patients have had success with three strategies:

1. Identifying the causes and treating them:  Since we know what has been causing our excess RT3, one obvious strategy is to treat what’s causing it. Since it can take time to raise low iron or B12, or improve low cortisol,  or lower high RT3, one strategy for some has been to lower the desiccated thyroid, which lowers the T4…and all the while treating the causes.  Changing your lifestyle can be key, as well, such as greatly improving your food choices, facing an alcohol addiction, stop smoking, and avoiding high stress.
2. Using a good liver cleanse/support product, plus Selenium:  Since the bulk of RT3 is made in the liver, some have lowered their high RT3 by using a good liver cleanse, especially those with Milk Thistle. You may have to DOUBLE the recommended amount to get the lowered RT3.  Milk Thistle can supposedly lower ferritin, so patients are adding iron to their supplementation, or raising what they are already on. Also make sure your Milk Thistle comes from the seeds. Milk Thistle not from the seeds can have an estrogenic effect. Also, there is a lot of research which proves that low selenium can increase RT3.  So patients supplement with Selenium to stop that fact.
3. Going on T3-only:  T3-only dosing can have its challenges since you have NO storage T4 to do the job of providing T3 for you.  But it can work, and is especially important if you haven’t succeeded it lowering your chronic RT3 in any other way. Cytomel is a very popular brand of T3, as is Mexican Cynomel, for patients.

How do I dose T3 if I choose the latter method?  Excellent patient information is found here. 

How long does it take to lower harmful levels of high RT3 when using T3-only? By labs, patients have noted good lowering in about eight weeks. Some need twelve.

There is also an excellent T3 chapter in the Revised STTM book which can be taken into your doctor’s office and referred to, as needed, as you work to teach your doctor about its use.

Have more good research studies for this RT3 page? Send them to STTM via the Contact link below.

Where can I talk to others about this?? Go here.