Thyroid Antagonism from Reverse T3 Dominance and its Link with Constipation – Thyroid & Gut Health

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Updated: January 2021

I recently reviewed one of my comprehensive blood work panels with one of my patients. She had a completely normal thyroid panel.

When I say normal, I mean her thyroid panel looked perfect. Keep in mind that on my thyroid panel, I run 9 tests. My goal is to leave no stone unturned with my patients.

However, she had all of the

Classic Hypothyroid Symptoms

  • Coarse, dry hair
  • fatigue
  • Dry, rough or coarse skin
  • Thinning hair or hair loss
  • Difficulty losing weight
  • Muscle cramps
  • Irritability
  • Muscle aches
  • Sensitivity to cold temperatures
  • Feeling of being week or “unwell”
  • Constipation
  • Depression
  • Memory loss
  • Abnormal menstrual cycles
  • Decreased libido (low sex drive or desire)
  • Weight gain

When I order a blood draw on my patients, all of the lab tests take different amounts of time to start coming back to my office. Some tests like homocysteine, or the complete blood chemistry come back very quickly. Others can take up to 2-3 weeks.

Are Thyroid Tests Reliable?

Like I said, all of the thyroid tests came back perfect. Or should I say the first 8 thyroid tests came back perfect. Her TSH looked great. She had plenty of T4. Her Total and Free T3 were right on the mark.

Everything looked great but the patient told me that she didn’t feel great. She suffered from almost all of the hypothyroid symptoms listed above.

Is it possible to suffer from “hypothyroidism” and have a “normal” thyroid panel?

What are TSH, T4, and T3 Thyroid Hormones?

First, let’s do a little education on thyroid hormones. The pituitary gland makes thyroid stimulating hormone (TSH). TSH goes to the thyroid and causes it to produce mostly T4 and a small amount of T3. T4 is considered an inactive form of thyroid hormone.

So, the thyroid mainly produces a hormone (T4) that is a biologically inert storage form of thyroid hormone. T4 has to be converted to T3 in the tissues of the body. T3 is the biologically active form of thyroid hormone. It’s the mover and shaker.

Thyroid Hormone Conversion is the Key

Here is the most important take home from this entire article: The function of thyroid hormones in the body comes down to proper T4 to T3 conversion.

Thyroid hormone conversion takes place mainly in the liver, gut, brain, and skeletal muscles. You can have all of the T4 necessary but if it doesn’t get converted to T3, it can cause symptoms of hypothyroid or “hypothyroidism”.

Why are T3 Levels so Important?

So, if you have intestinal dysbiosis in your gut, it can affect your T3 levels. If you have a fatty, congested, and backed up liver, it can affect your T3 levels. If you have some rhabdomyolysis (breakdown of skeletal muscles) that is being caused by your cholesterol medication, it can affect your T3 levels.

I’m sure you get the point by now. Several components affect T3 levels and when you don’t have enough T3, it can be a sign of hypothyroidism and you can suffer from any or all of the symptoms listed above.

Remember though, this patient had plenty of T3. She was good to go! However, when you have enough T3 in your bloodstream, your pituitary senses the good levels and will make less TSH.

When you don’t have enough T3, the pituitary will make more TSH to stimulate the thyroid gland to make more T4. In a proper functioning system, the T4 gets converted to T3 and things are great.

It’s a delicate balance that is always going on to preserve homeostasis or balance in the body.

Now that we understand that T3 is mainly a product of T4, and proper conversion of T4 to T3, we are ready to talk about another player in the game.

What is Reverse T3

The 9th and last test to come back to me was a thyroid test called Reverse T3. To me, Reverse T3 is a fascinating phenomenon. At the molecular level, Reverse T3 is a mirror image of T3. It looks the same but is slightly different.

Reverse T3 can cause big problems. The reason: Reverse T3 is a T3 antagonist. In plain English, Reverse T3 will block T3 from doing its job!

T3 is the biologically active form of thyroid hormone in the body and Reverse T3 can block T3 from doing its many, many functions.

How is Reverse T3 Like Carbon Monoxide?

The way I explain it to my patients is this: Most people are familiar with carbon monoxide poisoning. Red blood cells bind oxygen. But, carbon monoxide has a higher affinity to the oxygen receptors on the red blood cells.

So, carbon monoxide will bind to the oxygen receptors and block oxygen from binding to them. This is how carbon monoxide poisoning can kill you. The carbon monoxide keeps oxygen from binding and you suffocate.

Reverse T3 is like carbon monoxide. It has a higher affinity for the T3 hormone receptors than T3 has, so it will occupy the T3 receptor and block T3 from getting in.

Symptoms of High Reverse T3

High levels of reverse T3 may not actually kill you outright but it can create depression, brain fog, extreme fatigue, constipation, weight gain, etc… and all of the symptoms of hypothyroidism may not make you feel like you are “alive”.

So, the answer to the question, “Can someone suffer from hypothyroidism even when their lab tests look good?” is, Yes!!!

What is Reverse T3 Dominance

When your Reverse T3 is too high, then it will block the active T3 from doing its job throughout your entire body. This phenomenon is called Reverse T3 dominance.

Reverse T3 dominance can cause any of the symptoms listed above. Of importance here is constipation. T3 is one of the factors that regulates motility of the digestive tract.

When your Reverse T3 is too high, you will have low to no motility because T3 is getting blocked from Reverse T3 dominance. Therefore, you can suffer from constipation.

Constipation and Hypothyroidism

In the United State, constipation affects approximately 42 million people according to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK).

Constipation has many risk factors including: hemorrhoids, cancer, malabsorption, anal fissures (tears), anal prolapse (part of the rectum sticks out of the anus), and malnutrition.

Yes, I said it again:  malnutrition.  I write about malnutrition a lot because of the consequences.  If you have diarrhea, you are malnourished.  I don’t think I need to explain the reason why.

When you have constipation, fecal matter just sits in your intestines and isn’t moving through.  Feces is waste.  When you have a bowel movement, you are eliminating waste from your body.  When you are constipated, you are retaining toxic material that doesn’t belong there.

Constipation can be caused by many factors. I believe that reverse T3 Dominance is one of the common causes and often goes untested and unidentified.

My patient told me that she has been telling her husband for a long time that she felt that she suffered from hypothyroidism but her Drs. told her that her “thyroid looked fine”.

Thyroid Hormone Conversion Problem

Her Drs. were right! She didn’t have a true thyroid problem. If she had not come to me and I hadn’t performed a comprehensive and thorough thyroid workup, she most likely would have never known that she in fact is hypothyroid.

The moral to the story: She doesn’t have a “thyroid” problem. Her thyroid gland is working great. However, she does have a thyroid hormone conversion problem in her body that had gone undiagnosed.

There are nutrient deficiencies that can create poor thyroid hormone conversion as well as chronic inflammation, stress, infections, and other causes.

Now, she and I are working together to get her body less inflamed. We are focusing on shifting her body from a catabolic (breakdown) state, to an anabolic (building up) physiology where her body isn’t in a chronic cycle of nutrient deficiency and depletion.

An interesting side note is that my patient proof read this article for me. I asked her if there were any additional comments I should make about someone who is going through Reverse T3 dominance and having constipation or any of the other symptoms above.

She said, “Yes, talk about how your whole body feels dry or dehydrated.  Your whole body just feels dry.”

Health is Happiness,

Dr. Keith Currie

What patients think:

I have Rheumatoid Arthritis which is pretty crippling. I have been living in pain for a long time. I couldn’t even roll myself over in bed, my husband had to help me. I can do that now so that’s a blessing right there. Dr. Currie has helped me a lot.

by - Mary M., South Carolina

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