Why Hypothyroidism is Worse with Iron Deficiency

Why Hypothyroidism is Worse with Iron Deficiency

*This article was recently updated on January 25th, 2019 with more information*

Did you know that Iron deficiency may be one of the reasons you DON'T feel better on your medication?

Iron deficiency is one of the most common nutrient deficiencies seen in hypothyroid patients (even if they are currently taking thyroid medication). 

Not only is it common, but it is frequently misdiagnosed and/or missed. 

You see:

​Most Doctors are trained to look for Iron deficiency anemia, and NOT just iron deficiency by itself. 

Patients with Hypothyroidism deserve special treatment because of how important Iron is for adequate thyroid hormone production.

Let's talk about how to diagnose iron deficiency, what tests to order and the supplements I give to my patients to reverse iron deficiency...​


Thyroid Function and Iron Status

​Iron is required for proper thyroid function.

Studies are clear on the matter (1).

Iron deficiency and thyroid function

Not only is iron required for the creation of thyroid hormone (2), but low iron levels are also associated with low levels of free T3 (3) (which is THE active form of thyroid hormone). 

​This means that in hypothyroid patients low iron levels = low T3 = tissue level hypothyroidism. 

This may explain why some patients still experience the symptoms of hypothyroidism despite taking "adequate" thyroid hormone replacement.

​The association of iron and TSH level is clearly defined in the graph below: 

relationship between iron and transferrin saturation

You can see the inverse relationship between transferrin saturation and the TSH. 

As your transferrin saturation falls (4), the TSH rises indicating a state of hypothyroidism. 

Transferrin saturation is a lab test that helps determine how much of the serum iron is bound vs unbound and low levels can help indicate low iron levels in the serum. ​

Iron is required for thyroid hormone production due to its effects on heme-dependent thyroid peroxidase. ​

In addition, low iron has been shown to impact the effects of iodine supplementation (5).

Meaning the lower your iron levels are the less likely you are to utilize iodine if you are supplementing with it. 

This can lead some patients to believe that iodine supplementation is not working for them when in fact it may be due to their iron status instead. ​

The worse part about iron deficiency is that it is so commonly missed.

Most providers will only check iron levels if they find that you have grossly abnormal Hemoglobin or Red blood cell levels - indicating anemia.

But much like thyroid hormone levels, lower levels of hemoglobin can indicate a problem and lead to symptoms of both hypothyroidism and Iron deficiency...​

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​Symptoms of Low Iron & Hypothyroidism 

So how do you know if you have iron deficiency or low ferritin?

By the way, low ferritin levels can indicate early iron deficiency because ferritin acts as a marker of iron stores in the body.

It's also one of the best ways to assess for iron deficiency in patients (but we will discuss this more in depth later). ​

​Iron deficiency by itself causes a host of symptoms which we will go over. 

But in addition, iron deficiency also makes thyroid function worse.

This complicates the picture by causing symptoms of both iron deficiency and symptoms of hypothyroidism in hypothyroid patients. ​

If you have hypothyroidism but you are suffering from any of the symptoms below, then you should get your iron status checked. ​

Symptoms of low ferritin

Symptoms of iron deficiency in hypothyroid patients: 

  • Fatigue
  • Weakness
  • Pale Skin (especially in the creases of the palms)
  • Shortness of Breath
  • Dizziness, especially with exertion or with exercise
  • Cravings for ice (to eat or chew it)
  • Cold hands and feet
  • Brittle nails and thin/dry Hair
  • Headaches

​You will notice that many of these symptoms also closely match with the symptoms of hypothyroidism. 

That is why the diagnosis of iron deficiency in hypothyroid patients can be difficult. 

Often times iron deficiency is masked by symptoms of hypothyroidism, but this can be easily identified by checking the right lab tests. 

Symptoms of Hypothyroidism​

This list of symptoms is to compare to the symptoms of iron deficiency.

This can help give you an idea as to which you may be suffering from (or perhaps identify that you do indeed have both conditions).

Remember that iron deficiency itself can worsen hypothyroidism as well. ​

One of the big reasons that Iron deficiency causes worsening hypothyroid symptoms is because it leads to decreased T4 to T3 conversion.

Remember that T3 is the active hormone in your blood so you may have "normal" levels of T4 but unless you are converting that T4 into T3 it's basically useless.

"Typical" symptoms of hypothyroidism: ​

  • Fatigue especially after sleeping 8-10 hours a night or feeling like you need to nap daily
  • Weight gain or the inability to lose weight
  • Mood issues such as mood swings, anxiety or depression
  • Hormone imbalances such as PMS, irregular periods, infertility, and low sex drive
  • Muscle pain and joint pain
  • Cold hands and feet, feeling cold when others are not or have a persistently low body temperature
  • Dry or cracked skin, brittle nails, and excessive hair loss

Patients with a combination of iron deficiency AND hypothyroidism may notice that their hypothyroidism symptoms get WORSE the lower their iron gets. 

The good news is that these symptoms do tend to decrease with proper iron supplementation and replacement. ​

Hashimoto's Thyroiditis and Iron Deficiency

​Do patients with Hashimoto's also have issues with iron?

The answer to this question is a resounding YES.

While patients with Hashimoto's thyroiditis are not your garden variety hypothyroid patients, they still tend to have many of the same issues that hypothyroid patients experience.

The lack of thyroid hormone (or fluctuating thyroid hormone levels as the case may be) is still enough to cause changes to the stomach acid levels and alter iron absorption.

thyroid metabolism reset poster for side bar

Proper iron levels are still required for optimal thyroid function in both hypothyroid and Hashimoto's patients.

If you have Hashimoto's make sure that you are also following the information outlined in this post so you can get evaluated as well.

Is your Iron Level Optimal?

When we talk about nutrient status we really need to differentiate between having "normal" levels and having "optimal" levels.

Most physicians are trained to look at reference ranges and base treatment off of lab values that fall outside of the reference range. 

But unfortunately, the reference range for many nutrients (iron included) spans a wide range. 

Take serum iron for instance:

The reference range is from 40-190 micrograms/dL. 

Your doctor will most likely only care if you are less than 40 or higher than 190. 

But that leaves so much room in between where you may feel sub-optimal. 

The difference between 50 and 150 is HUGE. 

And your doctor may ignore your iron levels if your value is 45, but they may treat you if you are 38. 

With this concept in mind, and when I give you my recommended reference ranges, I am always referring to the "optimal" levels for iron in your body. 

The optimal levels allow your thyroid to function optimally. 

Because most physicians do NOT evaluate your labs with the optimal ranges in mind the chances are very high that you have suboptimal iron levels. 

When it comes to evaluating for Iron deficiency I recommend these tests...

(Remember that you can ask your Doctor to order these tests at your next visit, he/she shouldn't have a problem doing this for you)​

Check Ferritin, Serum Iron and TIBC

To get your iron status evaluated you need ALL of the following lab tests: ​

  • Ferritin - This number represents the total storage of Iron in your body
  • Serum Iron - This represents circulating Iron in your blood
  • TIBC (Total Iron Binding Capacity) - This represents your body's ability to carry Iron (It will go UP when iron is low)
  • Percent Saturation - This is the Ratio of Serum Iron and TIBC

Your Doctor will be used to ordering these labs, but the tricky part is in t​he interpretation. 

I Find that patients typically feel better when they fall within these ranges to both reduce symptoms and increase T4 to T3 conversion. 

Optimal iron levels for hypothyroid patients: ​

  • Ferritin - Optimal Levels = 40-50
  • Serum Iron - Middle of the reference range
  • TIBC (Total Iron Binding Capacity) - Middle of the Reference range
  • Percent Saturation - 35-38%

Hypothyroid Patients do Better on Liquid Iron

So what do you do if you find yourself with sub-optimal levels?

​I find most Hypothyroid patients have ferritin levels in the 20-30 range with a host of symptoms as described above. 

In my practice, I've found that most thyroid patients respond better to liquid formulations of iron. 

Many hypothyroid patients have issues with absorption due to a combination of other nutrient deficiencies and low stomach acid.

Taking liquid iron can help increase absorption.

In addition, liquid iron is much less likely to cause issues with constipation, and many hypothyroid patients suffer from constipation due to SIBO/SIFO

How to Supplement with Liquid Iron & Iron Capsules

Why I like it

May Boost Energy Levels

Up to 50% of Hypothyroid patients are deficient in iron

Helps promote thyroid conversion & function

Generally works within 1-2 months

How to tell if you Need it

Check your iron studies and only supplement if your levels are sub-optimal or low: 

  • Ferritin - Optimal Levels = 40-50
  • Serum Iron - Middle of the reference range
  • TIBC (Total Iron Binding Capacity) - Middle of the Reference range
  • Percent Saturation - 35-38%
Low iron studies patient case study
How to Use

  • Liquid iron: Start with 10 ml each day, do not exceed 20 ml per day (if you take more than 1 dose per day make sure to split it apart from one another and take at least 4 hours away from your thyroid medication)
  • Iron capsules: Start with 1 capsule of iron and increase up to 3 per day as tolerated and based on your serum iron/ferritin levels (take at least 4 hours away from your thyroid medication)
My Recommended Brand and Product:

Use liquid iron if you have intestinal issues such as gas, bloating, diarrhea, constipation or if you have previously failed capsule forms of iron: 

Use this capsule form if you don't tolerate the liquid iron version above (some patients have various symptoms on liquid iron such as teeth pain or simply can't tolerate the taste or texture of the liquid): 

If you choose to take Iron of any kind just make sure to take it with Vitamin C to help increase absorption (6).

How to Take Iron Supplements

​I've found that patients often do better when they do the following:

  • Take your Liquid Iron away from food
  • Avoid taking other supplements, coffee or tea when you take your Iron supplement (These may limit the absorption of iron)
  • Take your supplement with Vitamin C or a glass of Lemon water (Both of these help your body absorb iron)
  • Take your Iron with B vitamins - B Vitamins help with absorption of iron
  • Take your Iron at least 4 hours away from your thyroid hormone medication (if you are on thyroid hormone) - I usually recommend taking one at night and the other in the morning

​Take your iron at least once per day.

If a patient has VERY low Ferritin and Iron levels you may need to take iron several times per day for a few months. 

Track your Progress by Following Ferritin Levels

When taking iron it is very important that you constantly monitor and track your progress every few weeks to months. 

Not tracking may lead to really high levels of iron, or you may miss the fact that your body doesn't tolerate the form of iron you are using.

​Iron levels are easy to track. 

After 4-6 weeks you can ask your Doctor to recheck your iron panel (list above). 

​Continue taking your dose of Iron until you see improvement in your symptoms and your lab tests. 

Remember that Iron is like Goldilocks nutrient. 

Too little is harmful to the body, but too much can be just as harmful.

You do NOT want elevated Iron stores in your body - this can lead to inflammation and many other conditions (7).

What if your Ferritin levels are Elevated but you Have Low Serum Iron?

This can happen, and it is something I see in many patients. 

Ferritin is not only a marker of total body stores of Iron but it is also an acute phase reactant. ​

Ferritin is an acute phase reactant

That means that Ferritin can be elevated in states of inflammation. 

This is especially common in patients with Hashimoto's and other hormone imbalances that lead to inflammatory states in the body. 

The problem is that this can fool you into thinking that iron stores are "high" when in reality they are low, the body is just in a state of inflammation.

For these individuals, I would recommend discussing this with your Doctor. You will need to evaluate other inflammatory markers like ESR and CRP before you make a decision to supplement with Iron or not.

I will also recommend patients that fall into this category to start with an anti-inflammatory diet to reduce whole body inflammation as well as anti-inflammatory supplements. 

Recap & Final Thoughts

Hypothyroidism and Hashimoto's patients frequently present with sub-optimal iron levels.

Iron is critical to thyroid function in the body and these sub-optimal levels can lead to symptoms that may mimic the symptoms of hypothyroidism.

Because of these changes, it is important that you have your iron levels evaluated with "optimal" ranges in mind.

If you are suffering from hypothyroidism and think you may also have sub-optimal iron levels, then you should start by getting a full iron panel in your body.

Replacing your iron levels is critical for optimal thyroid production, for increasing T4 to T3 conversion and for helping your thyroid hormone be more effective.

And while you are at getting your Iron levels checked, don't forget to check Vitamin B12 and Vitamin D! These are also very common nutrient deficiencies in Hypothyroid patients. ​

FAQ about Iron and Hypothyroidism

Can iron deficiency cause hair loss?

Yes, iron is required for proper hair growth and may be one of the main causes of hair loss in patients with hypothyroidism and Hashimoto's thyroiditis.

Unfortunately, low thyroid hormone itself can also cause hair loss or changes to your hair which can make diagnosis difficult.

Many patients with hypothyroidism who also have hair issues (hair loss, damaged hair, etc.) have a combination of both hair loss AND low thyroid hormone.

Replacing iron levels and replacing thyroid hormone in the body are both required for optimal hair growth. 

You can read more about how to address hair loss and regrow your hair if you have hypothyroidism in this article

Will iron deficiency make weight loss more difficult?

​Iron deficiency in hypothyroid patients may make weight loss more difficult. 


This largely has to do with the interaction between iron and thyroid hormone.

When iron is low your thyroid function will also be blunted.

Low iron = decrease thyroid function = decrease metabolism = weight gain

So the connection is there, but it occurs in an indirect manner. ​

For best results, and if weight loss is your goal, make sure that you replace ALL nutrient deficiencies.

You can find a list of nutrients required for proper thyroid hormone production and function in this post. ​

What is ferritin?

Ferritin is a marker of iron stores in the body.

It is also a marker of inflammation and is often elevated in inflammatory states. 

At low levels, it is very sensitive for iron deficiency, but at higher levels, the value becomes less predictive of iron status and more predictive of inflammatory states. 

Is ferritin required for hair growth?

Yes, a ferritin level of at least 30 is required for optimal hair growth (8). Studies have shown that levels less than 30 may result in hair loss. 

It is also important to note, though, that hypothyroidism can ALSO contribute to hair loss. 

Many patients with thyroid issues are often undertreated with thyroid medication and these patients may also suffer from iron deficiency as well. 

If this happens to you, you must treat BOTH issues in order to realize hair growth. Doing one without the other will often not be sufficient. 

How long will it take for my iron/ferritin to increase?

As long as you are absorbing the iron supplements that you are taking then you should see an improvement in both measures within 2-3 months. 

You can and should test your ferritin/iron studies around the 8 week mark for progress. You may not see a large bump in either at that time, but you should see an upward trend (even if minor). 

If you do not see any positive change then you may need to evaluate the type of iron you are taking. 

For instance:

Are you taking pills or are you taking liquid? What type of iron are you taking? How much are you taking? Is your intestinal tract allowing for absorption?

Answering these questions may help you make changes to your regimen. 

What if iron supplements don't work?

For various reasons, you may be someone that doesn't respond to oral iron supplements. 

If you fall into this category then you may need what is called an iron transfusion. 

This is a small procedure where iron is directly transfused into your bloodstream. 

It is VERY effective at increasing iron stores in your body but it is typically only used for extreme cases. 

For those suffering from acute iron deficiency, those who are having trouble with constant bleeding (from any cause), or those who simply don't respond to typical iron supplements. 

This procedure does carry some risks with it so it is typically performed in a hospital like setting. 

If you find that you are not responding to iron supplements, or if you fit any of the categories listed above, you may want to speak to your doctor about a transfusion. 

Can iron deficiency cause anxiety?

Iron deficiency may exacerbate symptoms of anxiety and may indirectly lead to panic attacks.

Low iron leads to increased shortness of breath which may make certain patients feel like they are unable to catch their breath.

This can trigger a cascade of events leading to a panic attack or anxiety. ​

Now I want to hear from you:

​Have you been suffering from Iron Deficiency as well as Hypothyroidism?

What have you done to increase your Ferritin levels?

What didn't work for you?

Leave your comments below!

Additional resources:

Low iron levels result in low cortisol levels (9).

Low iron causes decreased T4 to T3 conversion (10).

Low iron alters the sympathetic nervous system (11).

References (Click to Expand)

Westin Childs

Dr. Westin Childs is a Doctor of Osteopathic Medicine. He provides well-researched actionable information about hormone-related disorders and formulates supplements to treat these disorders. He is trained in Internal Medicine, Functional Medicine and Integrative Medicine. His focus is on managing thyroid disorders, weight loss resistance, and other sex hormone imbalances. You can read more about his own personal journey here.

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