Treating Hashimoto's and Reverse T3

If you are not a physician, please keep in mind: this stuff is complex, especially if you are not trained in scientific language and the specific way doctors think about medical issues. Scientific proof is not nearly as black and white as people think, and we frequently have to use inference and extrapolation to decide what applies in a specific situation and for a specific patient.  In order to make treatment decisions for individual people sometimes we have to consider evidence that is not nearly as absolute as we would like. This is where experience, advanced medical training, and consideration of the relative benefit versus risk comes into treatment recommendations. This is not medical advice. If you have a thyroid-related diagnosis or symptoms, please talk to your doctor about any concerns you may have.

Today I am going to continue discussing things that I really wish more doctors knew about thyroid. If they did I wouldn’t have spent 20+ years undiagnosed, exhausted, cold and just feeling worn out.   These “pearls” so to speak, are bits of the knowledge I use to help people get better results from their thyroid medications.

In the last post, I mentioned Hashimoto’s thyroiditis, and it turns out not so many physicians know very much about it, how to diagnose it, or that it can be treated, so let’s dive in a little.

Hashimoto’s is an autoimmune disease that turns up during times of extreme stress, like after having a baby for example, and it’s more common in women. It is actually extremely common, like maybe as many as 15% of women demonstrate the antibodies when tested, and as many as 4-5% will eventually develop symptoms,  so definitely the most common cause of hypothyroidism in the USA. 

In Hashimoto’s, the body makes antibodies against the thyroid hormone synthesis proteins thyroglobulin and/or thyroid peroxidase. The thyroid becomes infiltrated with lymphocytes as a result and can be acutely tender, and inflamed, leaving scar tissue as it waxes and wanes. Tight bands of scar tissue and then regrowth of thyroid follicles sometimes leaves nodules that sometimes can be mistaken for thyroid cancer, though they are not actually tumors. In other cases, the thyroid will just feel Rubbery and slightly enlarged instead of completely soft and non-palpable.

So I mentioned last week that for a long time, people may feel symptoms of low thyroid while their blood hormone levels are still in the reference ranges. This is because the main early problem that occurs is a malfunction of a particular enzyme in the thyroid called 5 prime deiodinase. This is the enzyme that removes a particular iodine from the T4 thyroid hormone molecule to make T3. 

Reverse T3

When this enzyme isn’t working well, a different deiodinase enzyme takes over and makes Reverse T3. This molecule is nearly the same as T3 but with the “wrong” iodine atom removed. When this molecule was first discovered it was thought to be just another inactive metabolite of T4. The FDA doesn’t even regulate Reverse T3, which is a problem because it frequently turns up as a contaminant in cheap generic thyroid hormones. But this turns out not to be inactive at all. Because it is so similar to T3, it binds the same receptors, the T3 receptors. The ones that control all the metabolic activation that thyroid hormone is responsible for, in every body tissue. Growth, energy production, protein synthesis. 

The problem is, ReverseT3 binds those receptors and blocks them. It’s a competitive inhibitor at the receptor site. The more of it is there, the less the actual T3 can bind and do its job. Originally, this was an adaptive response:  to starvation, severe illness or injury, or extremely high thyroid levels like are seen in Graves disease or thyrotoxicosis. It helps keep the body from just burning itself up. This has been best studied in critically ill ICU patients, and a low ratio of T3 to Reverse T3 is a strong predictor of poor outcomes in these patients. Giving T3 (liothyronine) can really help, but interestingly, giving more T4 (levothyroxine) has the opposite effect.

The milder form of this is frequently seen in patients with Hashimoto’s thyroid antibodies and in some other situations as well. Even if their free Hormone levels look ok, the high reverse T3 is blocking the action of thyroid hormone on the body.

Measuring ReverseT3  - Reverse T3 lab test is actually Total Reverse T3. There’s no test for Free Reverse T3. So when we look at the reference range, like total T3 it can be extremely broad because it’s mostly bound up by carrier protein. Luckily, the Ratio of Total T3 to Reverse T3 is quite consistent,  so can be used to treat patients.  A normal value of between 10 and 14 when you divide T3 by Reverse T3 seems to be where patients really feel well, and where truly normal patients live. And maintaining the levels there will help patients consistently feel well, unless some other hormones are also disturbed. 

When does this milder form of Euthyroid sick syndrome manifest? 

There are actually several situations that can trigger it:

• Graves disease where T4 is really high - in this situation, it is actually protecting the body and heart from the toxic effects of too much thyroid. 
• Hashimoto's - because of fluctuations in T4, which generally aren’t as high as in Graves disease but can still trigger elevated Reverse T3
• Starvation, extreme illness, or injury
• Extreme stress
• Loss of sleep
• Dieting
• Genetic mutations in 5’deiodinase
• Too much ingested T4
  
  

Since T4 is the Substrate (or precursor) for RT3 if the patient is taking Levothyroxine, sometimes just dividing the dose, like we discussed last week, can help lower the production of RT3. Sometimes T4 has to be lowered and divided. And giving T3 is the other way to force that ratio up. Keep in mind all the things about taking thyroid hormones that we mentioned last week, in particular, that prescription T3 has an even shorter half-life than T4, and must be given more than once a day for patients to really benefit.

Stress

And finally, let’s talk about extreme or prolonged stress. Elevated ACTH (the brain chemical that signals your body to make more stress hormones), suppresses TSH and therefore suppresses thyroid function (it’s like your body is going into hibernation.) This is because your body can’t tell the difference between a calorie-restricted diet and actual starvation, or between being stressed out because of a stressful job or home life,  from an extreme illness or injury where it needs to conserve energy or die. Which, if you aren’t actually sick or injured or starving, makes it even harder to manage your life, because it adds chronic exhaustion to the list of things causing you to be stressed out. 

There are more ways that chronic stress harms or dysregulates thyroid function as well. Those are beyond the scope of this discussion, but suffice it to say if you’re having symptoms of low thyroid and stress, it is likely that your thyroid is not working well even if your labs look pretty good. There ARE things that can be done to fix this, that we can address in a future discussion.

Don’t forget, if you are suffering from thyroid issues that haven’t been fixed by what you’ve tried so far, my new office is open for business and taking new patients now! Check it out at www.danagibbsmd.com.

I'm Dr. Dana Gibbs, encouraging you to take charge of your hormonal health. For more tips and updates, sign up for my newsletter at https://www.danagibbsmd.com/email-list-form. If you're in North Texas and struggling with thyroid or chronic fatigue issues, visit https://www.danagibbsmd.com/cim-medical for a new patient evaluation.