One Key Reason Why Your Thyroid Hormone Is Not Working

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One Key Reason Why Your Thyroid Hormone Is Not Working

Low iron causes hypothyroid symptoms.

If you are still experiencing symptoms of hypothyroidism despite taking a thyroid hormone, a recent study shows promise. The study showed that two-thirds of women with the above condition, who brought their ferritin levels (or functional iron in their blood) above 100, saw their persistent symptoms relieved. Consider testing your ferritin and supplementing it before adding on another medication. Interestingly, 100 is not a cutoff for healthy iron levels in most blood tests, so make sure to take a closer look.

Episode Intro

Dr. Michael Ruscio, DC: Hi, this is Dr. Ruscio. Let’s discuss a simple nutritional intervention that can help maybe two-thirds of women better respond to their thyroid hormone. I’d like to share the results of a study with you in which they make the comment,

In two-thirds of women with persistent symptoms of hypothyroidism despite appropriate levothyroxine therapy, restoration of serum ferritin above 100 µg/l ameliorated symptoms.

So when women who have hypothyroidism are on levothyroxine and not feeling well, supplementing them with iron and getting their ferritin (a marker of iron) above 100 relieved the symptoms in two-thirds of those women. This is exciting.

[Continue reading below]

Dr. R’s Fast Facts Summary

Nutritional intervention that can help women better respond to their thyroid hormone

  • If you are on Thyroid medication and you are not feeling well there is a 75% chance that supplementing with Iron could get you feeling better.
  • Specifically testing ferritin and getting ferritin levels to above 100 with an iron supplement.
  • Ferritin is a marker in the iron family that tells you the functional iron status in your blood, tied to anemia.

Here are two supporting studies

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And I fact-checked this, because I wanted to see where the conclusion is coming from. So we have to look at another paper here. And this study did, in fact, find that restoring ferritin to 100 alleviated symptoms in roughly 75% of women who are non-responsive to levothyroxine. This was a smaller study, 25 women. And it took about 6 to 12 months for the ferritin to become normal.

Link Between Iron & Thyroid Medication Response

Now, what is ferritin? Ferritin is a marker in the iron family that tells you, essentially, the functional iron status in your body. It’s tied in with anemia. And for women who are suffering with hypothyroidism, there is a lot you have to contend with when you go on the internet. There are many theories and philosophies. Much of this is well-intentioned. A lot of it also unfortunately is speculation. So having evidence to help you parse the litany of claims can help you get to interventions that will have the highest probability of helping you.

In this case, while the results here are preliminary—only really one good study, maybe two others that hint at this—because this is a nutritional intervention, it’s something I would certainly consider if you’re a woman or a man on levothyroxine for your hypothyroidism. If you’re not feeling well, have your doctor run your ferritin.

Here’s the twist. 100 is not considered the cutoff for normal to abnormal. I believe some labs will have it around 25 or even 10. So the cutoff for ferritin is actually quite low on most labs. This is a case where a more nuanced examination that your blood work can be helpful.

Now, I want to be careful to say, there are some circles in integrative medicine that look at pretty much every value on lab work in a more narrow range. And I don’t know if that’s a fully tenable approach. In my experience, what ends up happening there is, you end up treating the lab instead of the patient, and it’s getting way too into the minutiae. But there may be a few choice markers, like ferritin, that having a closer look at may be helpful. And there’s actually a very strong theoretical basis for this.


Women who have hypothyroidism are also at higher risk for gastritis (or irritation to the lining of their stomach) which inhibits their ability to secrete hydrochloric acid. This ostensibly would lead to a decreased absorption of iron. And that’s been well-documented. I believe about 30% of patients may have something known as autoimmune gastritis. Now, what you do about that in terms of treatments is another story. And I wouldn’t be worried so much about that because I don’t believe there are really great treatments for it.

But if you’re a woman with hypothyroidism, you have a higher probability that the lining of your stomach and your ability to secrete acid may be slightly impaired. And this is why you may see deficiencies in iron. So this is why a population of those with hypothyroidism may be at higher risk for malabsorption of iron. As we see in this study, there may be this non-optimal absorption of iron. And by getting iron or ferritin specifically to 100 and above, that may resolve your symptoms.

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Optimize Your Iron (or Ferritin) First

So this is something that I would highly consider.

There’s something else here I want to juxtapose into this conversation, which is, many women or men who are on levothyroxine—which is a T4-only form of thyroid hormone—are told that the reason that they’re having symptoms is because they’re not on a T4 plus T3 medication combination. Now this can be levothyroxine, or Synthroid, combined with Cytomel. Or this could just be taking something like Armor Thyroid or Nature Throid.

And there is support for that argument. However, before going there, I would recommend looking at your ferritin levels and optimizing them to above 100. Because there are some people who actually end up feeling worse while they are on T4 plus T3. And theoretically, if you are not addressing iron, but you’re taking a different form of medication, you’re not really treating the source of the problem. Yes, a combination T4/T3 medication has merit, but in a hierarchy of interventions, I would place double-checking and optimizing your ferritin above in the order of operations, before considering a T4 plus T3 combination medication.

So to recap, if you’re on levothyroxine and if your dose is where it should be—meaning your TSH and your T4 are normal— and you’re not feeling well, consider testing your ferritin. And if your ferritin is not at 100, you can supplement with iron until your ferritin gets to 100. Then reassess your symptoms. There’s about a 70-75 percent chance that after doing that, your symptoms will be gone. If they are not gone, then you can consider other therapies. Namely, you can consider a T4/T3 medication. Or please don’t forget about the massive impact the gut has on your overall schematic picture, and consider doing a tune-up to optimize the health of your gut.

So, ferritin and hypothyroid… an interesting connection. Definitely something to consider if you’re struggling on your levothyroxine. And hopefully this can help you get healthy and get back to your life.

What do you think? I would like to hear your thoughts or experience with this.


I care about answering your questions and sharing my knowledge with you. Leave a comment or connect with me on social media asking any health question you may have and I just might incorporate it into our next listener questions podcast episode just for you!