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Is Iron Deficiency Making Your Hashimoto’s Fatigue and Other Symptoms Worse?

by | Jan 24, 2023 | Symptoms

Iron deficiency and hypothyroidism often go together, with many overlapping symptoms. They make each other worse. Iron deficiency can make you think your thyroid is the problem when iron is a real issue contributing to fatigue and many other Hashimoto’s symptoms. 

To make matters worse, “normal” iron and ferritin levels may not be optimal for you, especially with inflammation. Also, even women without Hashimoto’s struggle to increase their iron levels. By understanding the causes of iron deficiency, the symptoms, testing, and how to increase iron levels, you may be able to improve certain symptoms that don’t improve with thyroid meds. 

This article will teach you the ins and outs of iron deficiency and how to fix it at the root cause while living with Hashimoto’s.

what does iron do

Why is iron important, especially if you have hypothyroidism?

Aside from helping your red blood cells carry oxygen, iron helps with numerous other things in your body, including [1]:

  • Converting T4 (inactive thyroid hormone from your thyroid) to active thyroid hormone T3 [2]
  • Forming myoglobin, a protein similar to hemoglobin but in your muscles and heart muscles. Myoglobin carries extra oxygen for your muscles and heart so you can keep going a little longer.
  • Helping produce energy inside your mitochondria, your cellular energy powerhouse
  • Producing myelin, which helps your nerve cells transmit signals more efficiently
  • Producing and metabolizing neurotransmitters, the chemicals that help your brain cells communicate. This is why low iron can cause brain fog and irritability.
  • Helping your white blood cells grow and mature, along with some immune functions [3]

Needless to say, if you have low iron, the odds are high that you will struggle to manage your Hashimoto’s because you can’t turn levothyroxine (a common thyroid med) into active thyroid hormones very well. It’s one of those things that can fly under the radar when your thyroid labs appear normal.

Key Insight #1 Iron helps activate your thyroid hormones, carry oxygen throughout your body, helps energy production, and is also necessary for many aspects of brain function.

symptoms of low iron and anemia with Hashimoto's

How to know if you have iron deficiency or anemia

It’s possible, and very common, to have an iron deficiency without anemia [4]. The key difference is normal hemoglobin and normal red blood cells. Symptoms of low iron or anemia include the following:

  • Fatigue*
  • Weakness*
  • Pale skin and mucous membranes*
  • Shortness of breath
  • Heart palpitations
  • Restless leg syndrome
  • Cold extremities*
  • Dizziness*
  • Brain fog*
  • Chest pain
  • Headache
  • Irritability*
  • Sore tongue*
  • Muscle pain
  • Changes in menstrual flow, sometimes increased*

* common Hashimoto’s symptoms

As you can see, many of these symptoms overlap with Hashimoto’s symptoms. So, if your thyroid hormones appear optimal but you still feel the symptoms, it’s important to make sure your iron level is optimal. 

Key Insight #2: Many iron deficiency symptoms are the same as hypothyroid symptoms.

Lab tests that can indicate iron status

If you’ve been told by the lab, “Everything came back normal,” it’s probable that they may have only tested ferritin and done a complete blood count. However, there are other iron labs that can be illuminating. Here’s a full list of iron tests. 

Note: Certain medications can affect these lab results, so you want to make sure your doctor is aware of all your medications when they order the labs and interpret the numbers for you.

Key insight #3: Not all cases of iron deficiency show up as anemia or low ferritin, especially if you have inflammation. If all previous labs came up normal, ask for the full iron panel to rule out low iron without anemia or anemia of inflammation.

1. Complete blood count (CBC) 

Hemoglobin is an iron-containing protein that helps carry oxygen in your red blood cells. Iron-deficiency anemia can lower the amount of hemoglobin in your red blood cells. The anemia can also either reduce your number of red blood cells or average hemoglobin per cell, or both. 

A complete blood count is a panel of tests that measure:

  • How many red and white blood cells you have
  • Total hemoglobin combined from all your red blood cells.
  • Average hemoglobin for each red blood cell, which tells how well they can carry oxygen
  • Average size of your red blood cells, which indicates whether low iron could be affecting your red blood cell production

2. Ferritin

Ferritin is an iron storage protein. If your ferritin levels are low, it means your body is taking from the available storage in order to keep iron levels adequate. Ferritin can go down before you develop anemia. If you have anemia and your ferritin levels are low, iron deficiency is likely the reason.

The “normal” reference range for ferritin is 15−150 ng/mL. However, normal is not optimal and symptoms may start to arise below 30 ng/mL. 

The optimal range for ferritin is 50 ng/mL or higher. 

3. Serum (blood) iron levels

Serum iron is how much iron you have in the liquid part of your blood. The iron is usually bound to the protein transferrin. Low serum iron may indicate anemia of chronic diseases such as autoimmune diseases, irritable bowel syndrome, and cancers. 

4. Soluble transferrin receptor

Transferrin is a protein made by your liver. It carries iron throughout your body. When your iron levels are low, your liver makes more transferrin to bring more iron into your blood. Soluble transferrin receptor measures how available transferrin is to carry iron. 

5. Total iron binding capacity

Total iron binding capacity measures how well transferrin can carry iron in your blood.

If your CBC and ferritin levels are normal but you still feel symptoms, it’s a good idea to ask your doctor to do a full iron panel, including soluble transferrin receptor, as the other tests can indicate iron deficiency without anemia.

Iron panel patterns in various scenarios [4]

Test Iron deficiency without anemia Iron deficiency anemia Anemia of chronic disease Iron deficiency anemia + anemia of chronic disease
Hemoglobin N
Mean cell volume N or ↓ N (or mildly ↓)
Serum ferritin N or ↑ ↓ or N
Total iron-binding capacity N or ↑ ↓ or N N or ↑
Transferrin saturation ↓ or N ↓ or N
Soluble transferrin receptor N or ↑ N

N = normal, ↓ = decreased, ↑ = increased

What is iron deficiency anemia?

Iron deficiency anemia is when your iron is so low that it reduces your red blood cell production. As a result, you have fewer, paler, and smaller red blood cells and/or lower hemoglobin. The red blood cells that you still have also can’t do a good job carrying oxygen.

Hemoglobin is the red iron-containing protein in your red blood cells. Because iron is the central part of hemoglobin that helps it carry oxygen, iron deficiency anemia means you can’t deliver oxygen to your cells. So, you’ll have symptoms of low oxygen throughout your body.

Hashimoto's and anemia

Why does hypothyroidism cause iron deficiency or anemia?

Aside from not eating enough iron, most cases of low iron come from an inability to absorb it. Your body works very hard to keep iron within narrow ranges and avoid absorbing too much. This is why taking too much iron can cause nausea and vomiting.

Gut issues lowering iron absorption

Hypothyroidism commonly causes gut issues that lower iron absorption. These include:

1. Lower stomach acid due to hypothyroidism

Thyroid hormones stimulate cells in your gut and pancreas to produce stomach acids and digestive enzymes. Hypothyroidism tends to lower stomach acid and digestive enzymes. You need these to release iron from food, and the stomach’s acidity to turn iron into an absorbable form [5].

2. Stomach inflammation (gastritis)

Autoimmune gastritis (autoimmune stomach inflammation), termed thyrogastric syndrome, is common in Hashimoto’s patients. Up to 40% of Hashimoto’s patients have some form of stomach disorder. Similarly, approximately 40% of people with autoimmune gastritis also have Hashimoto’s [6]. The gastritis damages the stomach lining and the acid-producing cells. 

3. Gut lining dysfunctions and dysbiosis

Your gut lining absorbs nutrients. The inflammation and reduced metabolism in hypothyroidism can affect your gut lining, reducing its capacity to absorb nutrients, especially iron.  

The gut bacteria in your large intestine closely interact with your overall health, especially your digestive health. Many autoimmune patients have dysbiosis or imbalances of these gut bacteria. This dysbiosis can also reduce iron absorption [7].

4. Helicobacter pylori infection

Helicobacter pylori (H. pylori) is a bacteria that infects the stomach, and it may be found in 37.7% of Hashimoto’s patients and 66% of Graves patients, compared to 32% in the healthy population [8]. It can lower stomach acid and reduce iron absorption, causing an iron deficiency [9].

Anemia of inflammation or chronic disease

Also, since bacteria and parasites need iron to grow, if your body thinks it’s fighting off an infection, it will purposely avoid absorbing iron or making more red blood cells.

Anemia of inflammation or chronic disease is a subtype of iron deficiency anemia that responds poorly to iron supplementation. Because your body thinks it’s fighting off something as there is ongoing inflammation, it purposely avoids absorbing or producing more red blood cells [10]. 

Hashimoto’s can cause anemia or inflammation. In a study comparing hypothyroid and healthy people, 43% of overt hypothyroid people were anemic, compared to 39% in the subclinical hypothyroid and 26% in healthy control groups [11]. They had anemia with normal iron, folate, and vitamin B12 levels. 

Anemia of inflammation is another reason to address the inflammation, especially if you’re eating plenty of iron already.

How to address iron deficiency and iron deficiency anemia

how to improve iron absorption
With Hashimoto’s, you need to address iron levels and anemia holistically. Importantly, your body has a natural capacity for how much iron it can absorb in a day. Due to this normal limitation, replenishing iron stores by oral means often takes time and patience.

Key insight #4: Hypothyroidism can cause an iron deficiency and make it harder to replenish low iron. You need to address both hypothyroidism and gut health, and work to maximize your iron absorption to feel better.

Heal your gut

The first thing to do is to start improving your ability to digest and absorb iron. Otherwise, you’re fighting an uphill battle. Begin by healing your gut. It’s likely going to be best to work with a functional medicine practitioner to do this since there are many considerations and treatment approaches depending on your unique needs. 

Some of the most important gut healing steps to take include:

  • Discover and eliminate any food allergies or sensitivities, which you can do with the Autoimmune Paleo Protocol
  • Increase stomach acid production with a betaine HCl supplement
  • Treat gut infections such as parasites, candida, and H. pylori, and optimize gut flora health
  • Heal a leaky gut, and strengthen the gut barrier and mucus layer
  • Addressing stress, traumas, and sleep

Reduce whole body inflammation

Inflammation may explain why your iron levels won’t budge. Chronic inflammation can also cause fatigue, which only compounds fatigue from anemia and hypothyroidism.

Stress management, muscle building, adequate sleep, and an anti-inflammatory diet are musts if you want to balance inflammation in your body. See this article to understand Hashimoto’s inflammation and how to manage it.

Eat animal sources of iron

Iron from animal sources is called “heme iron” because it’s attached to the chemical structure called heme, which is naturally found in hemoglobin and myoglobin. Whereas, iron from plants and most supplemental sources is non-heme iron. Heme iron is much better absorbed than non-heme forms. Therefore, animal-sourced iron is superior to that from plant-based sources.

Around 15-35% of heme iron gets absorbed readily in your gut, without needing stomach acid or vitamin C [12]. Whereas, your gut may absorb just 2 – 20% of non-heme iron depending on numerous factors [13]. Some of the highest sources of heme iron are red meat and organ meats, like liver. Start getting these a few times a week if you are iron deficient.

Take vitamin C with iron supplements and plant-based iron

Iron supplementation along with increasing dietary iron is often the fastest way to improve your iron levels. You can get heme iron supplements, or elemental sources, such as iron sulfate, glycinate, malate, and citrate. The latter is more likely to be constipating. Since most women with Hashimoto’s already struggle with constipation, it might be best to focus on red meat and heme iron supplements. 

Iron supplements may also interfere with thyroid medications, so you want to take iron separately from your thyroid medications.

Vitamin C helps increase iron absorption and may ease constipation [12]. Taking vitamin C with any iron supplementation is a safe and science-based approach. It is especially important if you are taking a non-heme iron supplement.

Take an HCl supplement

Low stomach acid is commonly a factor in developing iron deficiency with thyroid problems. It’s important to replenish your stomach acid with betaine HCl to absorb iron and many other nutrients. 

Watch out for anti-nutrients that inhibit iron absorption

Most plant-based foods are beneficial but they also tend to come with components that can inhibit iron absorption, especially non-heme iron. For example:

  • Tannins, the bitter and astringent components mainly in coffee and tea, including some herbal teas [14]. If you’re a huge tea and coffee drinker, it may be time to cut back or at least consume them separately from your daily iron and red meat doses.
  • Phytates and oxalates found in grains, beans, nuts, and some fruits and vegetables. You can cut down the phytates in these foods through soaking, rinsing, and sprouting [15]. You can remove some oxalates in vegetables by cooking them. Some digestive enzyme blends, such as MassZymes (use code THYROIDSTRONG), contain phytase which can help break down some of these. 
  • Quercetin inhibits non-heme iron absorption [16]

Takeaway: Rely on heme iron and take your iron supplements separately from these anti-nutrient sources. If possible, cut down your anti-nutrient intake.

Retest every 3 months

Since your intestines have a limit on the amount of iron that can be absorbed in a day, retesting too frequently doesn’t give you great insight into the success of your treatment approach. Therefore, it’s not necessary to test iron and ferritin more often than every 3 – 4 months. If these numbers improve consistently, you know that you are now getting enough iron to replete your stores. This is the best sign you are on the right track.

If you’re anemic, it is important to retest RBC levels too, as this is the end result you want to see improve from higher iron levels. These cells die and new ones develop every 120 days. Therefore, you can see improvements at 3-month checks, but it may take 4 months or more for the RBC levels to increase to healthy levels, depending on the severity of your anemia.

Key Insight #5: Fixing an iron deficiency can take several months. It’s a good idea to retest iron and ferritin every 3 – 4 months.


Hypothyroidism and iron deficiency may commonly occur together and worsen each other. It’s possible to have iron deficiency causing symptoms without anemia. However, the good news is you can improve both with a holistic approach. Improving one will likely improve the other. 

Thyroid Strong supports your whole body health with our step-by-step approach to improving metabolism, balancing inflammation, and optimizing thyroid function. While it is mainly an optimized exercise program for women with Hashimoto’s, you’ll also get 20+ hours of content and interviews with functional medicine doctors diving deep into topics like iron deficiency. My goal is to help you take your power back to put Hashimoto’s into remission and thrive despite it. 

Affiliate disclaimer: This article contains affiliate links, which means that Thyroid Strong may earn a small percentage of your purchases if you use our links and coupon codes, while the prices will be the same or at a discount to you. This income supports our content production. Thank you so much for your support.


Article's References
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16 Lesjak, M., Balesaria, S., Skinner, V., Debnam, E. S. and Srai, S. K. S. (2019) Quercetin inhibits intestinal non-haem iron absorption by regulating iron metabolism genes in the tissues. Eur. J. Nutr. 58, 743–753.

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