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Iron Deficiency, Anemia, and Hashimoto’s Hypothyroidism

Learn the link between iron deficiency, anemia, and Hashimoto’s hypothyroidism and how it can effect your treatment plan.
Iron Deficiency, Anemia, and Hashimoto’s Hypothyroidism
Last updated:
12/31/2022
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If you have Hashimoto’s thyroiditis, the most common autoimmune disease in the U.S., it’s more important than ever to know your iron status. A deficiency in iron – including the more severe form called anemia – can significantly affect your thyroid gland function, negatively impact your treatment, and interfere with the relief of your symptoms.

In this article, we look at the latest findings about the link between iron deficiency, Hashimoto’s thyroiditis, and hypothyroidism and what you need to know.

What is iron deficiency anemia?

Iron deficiency is a deficiency in the nutrient iron, which is obtained through iron-rich foods or supplements.

When you don’t have enough iron, your body cannot produce enough hemoglobin for your red blood cells. Hemoglobin helps those cells transport oxygen to your tissues, glands, and organs.

This shortage of red blood cells is called anemia. About half of all cases of anemia are due to iron deficiency, and the condition is known as iron deficiency anemia.

Iron deficiency anemia is more common in women who menstruate, pregnant women, children, and people with conditions involving underlying bleeding and blood loss, such as ulcers.

It’s estimated that about 17% of premenopausal women and 10% of children in the U.S. are deficient in iron.

What are the symptoms of iron deficiency anemia?

The symptoms of iron deficiency include:

  • Fatigue
  • Shortness of breath
  • Weakness
  • Pale skin
  • Heart palpitations
  • Headaches and dizziness
  • A sore or inflamed tongue, mouth sores
  • Cold extremities
  • Poor appetite
  • Unusual cravings for items like ice, dirt, or starch, called “pica”
  • Tinnitus – a ringing or buzzing in the ears
  • Hair loss
  • Brittle, ridged nails

How is iron deficiency anemia diagnosed?

In addition to evaluating your symptoms, doctors diagnose iron deficiency anemia with blood tests that measure your iron levels and ferritin levels, among other markers, as defined in the Merck Manual

Normal serum iron:

  • 75 to 150 mcg/dL (13 to 27 micromol/L) for men
  • 60 to 140 mcg/dL (11 to 25 micromol/L) for women

Normal serum ferritin levels

  • 30 to 300 ng/mL (67.4 to 674.1 pmol/L)

According to Merck, “Low levels (< 12 ng/mL [27 pmol/L]) are specific for iron deficiency.” However, since ferritin is very reactive to inflammation and infection, in some patients, levels under 100 ng/mL indicate iron deficiency.

What is the treatment for iron deficiency anemia?

The treatment for iron deficiency anemia is twice-a-day iron supplementation. Typically, your iron and ferritin levels will be rechecked 30 to 60 days after starting iron supplements to assess the effectiveness of your dosage.

Remember that if you’re taking thyroid hormone replacement along with iron supplementation, you should take your iron at least three to four hours apart from your thyroid medication. Taking iron with thyroid medication can negatively affect your ability to absorb your medication properly.

In addition to supplementation, incorporating more iron-rich foods into your diet is also often recommended. Some of the best food sources of iron include:

  • Meats and poultry, including beef, lamb, organ meats, pork, chicken, and turkey
  • Poultry
  • Seafood, including oysters, mussels, and clams
  • Eggs
  • Chickpeas, pumpkin seeds, sesame seeds, and lentils
  • Dried fruit (raisins, apricots, prunes)
  • Iron-fortified grains, like bread, pasta, and cereal

Why is iron necessary for thyroid function?

Your body uses iron to help convert the storage hormone thyroxine (T4) into the active thyroid hormone triiodothyronine (T3). Low iron levels can reduce this conversion, reduce your levels of active thyroid hormone, and cause hypothyroidism or worsening thyroid symptoms.

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Also, when you’re hypothyroid, your body’s general metabolic slowdown can lower your red blood cell production, leading to anemia. Hashimoto’s patients are also often deficient in iron because malabsorption of nutrients – including iron – is common in people with autoimmune thyroid disease.

With all these connections, studies report that an estimated 45% to 65% of people with hypothyroidism have iron deficiency anemia, compared to only 29% in the non-hypothyroid general population.

According to researchers, even though people with thyroid disease have a higher prevalence of iron deficiency, it’s frequently overlooked by healthcare providers.

Research has shown that correcting and normalizing iron levels may be the only treatment needed to reverse some thyroid conditions and restore thyroid levels to optimal values. A study examined a group of patients – half had normal iron levels, and the other half had iron deficiency anemia. Before iron treatment, more than half the anemic patients also had subclinical or overt hypothyroidism. After iron supplementation, the treated patients were restored to normal thyroid function. This study showed that hypothyroidism could be reversible with iron treatment in people with iron deficiency anemia.

One study’s findings even reported that “it is always imperative to consider iron deficiency as an etiology for hypothyroidism.”

As noted, optimal thyroid hormone replacement may resolve the anemia in some hypothyroid patients with anemia. But, at the same time, some people with iron deficiency anemia don’t respond to iron supplementation, often due to their underlying hypothyroidism. Researchers have reported that treating patients with mild hypothyroidism and iron deficiency anemia improved both conditions. Treating those patients with either thyroid medication or iron alone had a significantly reduced impact on the conditions.

A note from Paloma

It’s recommended that women with Hashimoto’s or hypothyroidism – especially when they still have menstrual periods –have their iron regularly checked and take supplements to correct any deficiencies.

The test to determine if you have Hashimoto’s – the Thyroid Peroxidase Antibodies (TPOAb) test – is included in the Paloma Complete Thyroid Test kit. The Paloma kit helps you painlessly, conveniently, and affordably do a complete thyroid test panel at home.

Experts encourage doctors to increase their focus on the prevention, screening, and treatment of iron deficiency anemia in their hypothyroid patients – and hypothyroidism in their anemic patients – to “markedly improve the final outcome of these patients.”

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References:

Hu S, Rayman MP. Multiple Nutritional Factors and the Risk of Hashimoto’s Thyroiditis. Thyroid : official journal of the American Thyroid Association. 2017;27(5):597-610. https://pubmed.ncbi.nlm.nih.gov/28290237/

Ashraf TS, De Sanctis V, Yassin M, Wagdy M, Soliman N. Chronic anemia and thyroid function. Acta Bio Medica : Atenei Parmensis. 2017;88(1):119-127. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6166193/

Gökdeniz E, Demir C, Dilek I. The effects of iron deficiency anemia on the thyroid functions. J Clin Exp Invest. 2010;1:156–160. https://www.jceionline.org/article/the-effects-of-iron-deficiency-anemia-on-the-thyroid-functions-3153

Erdogan M, Mehmet E, Kösenli A, et al. Characteristics of anemia in subclinical and overt hypothyroid patients. Endocr J. 2012;59(3):213-20.https://www.jstage.jst.go.jp/article/endocrj/59/3/59_EJ11-0096/_article

Ravanbod M, Asadipooya K, Kalantarhormozi M, Nabipour I, Omrani GR. Treatment of Iron-deficiency Anemia in Patients with Subclinical Hypothyroidism. The American Journal of Medicine. 2013;126(5):420-424. https://www.amjmed.com/article/S0002-9343(13)00070-3/fulltext

Ghiya R, Ahmad S. SUN-591 Severe Iron-Deficiency Anemia Leading to Hypothyroidism. Journal of the Endocrine Society. 2019;3(Supplement_1).https://academic.oup.com/jes/article/3/Supplement_1/SUN-591/5483482

Are We Underestimating the Prevalence of Iron Deficiency? Columbia University Irving Medical Center. Published September 3, 2021. https://www.cuimc.columbia.edu/news/are-we-underestimating-prevalence-iron-defi

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Mary Shomon

Patient Advocate

Mary Shomon is an internationally-recognized writer, award-winning patient advocate, health coach, and activist, and the New York Times bestselling author of 15 books on health and wellness, including the Thyroid Diet Revolution and Living Well With Hypothyroidism. On social media, Mary empowers and informs a community of more than a quarter million patients who have thyroid and hormonal health challenges.

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