Is There a Connection Between Anemia and Hypothyroidism?

anemia, hemochromatosis, thyroid problems, iron deficiency anemia
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While a low red blood cell count (called anemia) is a common condition that can affect anyone, it tends to occur more frequently in people with hypothyroidism.

In fact, studies suggest that the rate of anemia in people with hypothyroidism is almost twice that of the general population. Moreover, anemia is often the first sign that leads a person to being diagnosed with hypothyroidism.

Types of Anemia in Hypothyroidism

Thyroid hormones stimulate the increase in red blood cell precursors.

So a deficiency of thyroid hormone (what happens in hypothyroidism) impairs the production of red blood cells in your bone marrow (the spongy tissue that lies in the center of certain bones).

When this occurs, anemia of chronic disease may develop, which is the most common type of anemia in hypothyroidism. Anemia of chronic disease is also referred to as anemia of chronic inflammation because it's associated with a wide variety of chronic inflammatory conditions, like infection, autoimmune disease,  kidney disease, or cancer. 

An autoimmune-related anemia called pernicious anemia may also develop in people who are hypothyroid. Research shows that pernicious anemia occurs in 10 percent of people with Hashimoto's thyroiditis (an autoimmune disease that causes hypothyroidism). 

In pernicious anemia, a person's stomach does not make a factor that is important for absorbing vitamin B12 from food.

Due to this lacking factor (called "intrinsic factor"), a deficiency in vitamin B12 develops. Since vitamin B12 is an important vitamin for making red blood cells, anemia then ensues.

Anemia from vitamin B12 deficiency may also result from intestinal absorption problems, which occur as a result of a decrease in gut motility in hypothyroidism.

Intestinal absorption problems in hypothyroidism may also lead to iron deficiency anemia or anemia from folic acid deficiency

It's interesting to note that iron deficiency can negatively affect thyroid hormone status (a two-way street). This is because iron plays an essential role in the production of thyroid hormone. So iron deficiency anemia (let's say from heavy menstrual bleeding) can depress thyroid function. 

Signs and Symptoms of Anemia

Most people with anemia, especially anemia of chronic disease, do not have symptoms. As the anemia progresses, though, symptoms and signs may develop, with the primary ones being:

  • Fatigue
  • Weakness
  • A pale appearance to the lining of lower eyelids
  • Fast or irregular heartbeats
  • Faintness and breathlessness
  • Tired, weak, or short of breath easily when exercising 
  • Short of breath at rest

Treatment of Anemia in Hypothyroidism

A person's anemia should resolve with treatment of the underactive thyroid, which entails taking thyroid hormone replacement medication.

In the case of iron deficiency anemia in hypothyroidism, the combination of thyroid hormone replacement medication (for example, levothyroxine) and iron supplements should result in resolution of the anemia.

For more severe cases, a blood transfusion may be required, but this is rare.

A Word From Verywell

Anemia in hypothyroidism is frequent, and sometimes the first clue that there is a problem with the thyroid.

If you have been diagnosed with anemia, be sure your doctor checks out your thyroid. The good news is that your thyroid function can be easily evaluated with a simple blood test: your thyroid-stimulating hormone (TSH).

Sources:

Erdogan M, Kosenli A, Ganidagli S, Kulalsizoglu M. Charactertistcs of anemia in subclinical and over hypothyroid patients. Endoc J. 2012;59(3):213-20.

Szcepanek-Parulska E, Hernik A, Ruchala M. Anemia in thyroid disease. Pol Arch Intern Med. 2017 May 31;127(5):352-60.

Surks MI. (2017). Clinical manifestations of hypothyroidism. Ross DS, ed. UpToDate. Waltham, MA: UoToDate Inc.