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Hypothyroidism and Anemia

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The Connection Between Hypothyroidism and Anemia

Anemia is a condition indicated by the insufficient concentration of red blood cells or erythrocytes to carry adequate oxygen to tissues in your body.

A widely prevalent condition can lead to various complications and it is connected with many health problems that affect a person’s quality of life.

In this post, we focus on a potential relationship between anemia and hypothyroidism.

How common is anemia?

Bearing in mind that anemia is linked with poor health outcomes, the prevalence of this condition is a major public health indicator.

Anemia is more common than people assume.

Figures reveal that 5.6% of Americans have anemia and 1.5% have moderate-severe condition. In the general US population, anemia is considered a mild public health problem. About 8.8% of pregnant women in the US are anemic.

Studies show that prevalence of anemia in American men and women is on the rise. On average, the prevalence of this condition in non-pregnant women was significantly higher than in men with a ratio of 7.6% vs. 3.5% respectively[i].

On a global level, anemia affects 1.62 billion people or 24.8% of human population. World Health Organization also confirms that non-pregnant women are a group with the largest number of persons affected by this condition[ii].

About 468.4 million non-pregnant women are anemic.

Symptoms of anemia

Like other conditions, anemia is indicated by various symptoms.

That said, symptoms of anemia are similar to those of other health problems thus explaining why many people don’t even realize they’re anemic.

While signs and symptoms of anemia depend on the underlying condition that contributes to it, the most common ones are:[iii]

  • Fatigue and weakness
  • A headache
  • Cold hands and feet
  • Yellowish or pale skin
  • Chest pain
  • Dizziness or lightheadedness
  • Irregular heartbeats
  • Shortness of breath
  • Difficulty concentrating
  • Leg cramps
  • Insomnia

Anemia in hypothyroid people

Both hypothyroidism and anemia are prevalent around the globe so it’s not that extraordinary to expect some kind of overlap.

What’s more, scientific research has confirmed that anemia is very prevalent in hypothyroid patients.

The Endocrine Journal published a study where scientists evaluated the frequency of anemia and etiology of hypothyroid patients. For this purpose, they enrolled 100 patients with overt hypothyroidism, 100 patients with subclinical hypothyroidism, and 200 healthy controls.

The difference between overt and subclinical hypothyroidism is that patients from the first group have high TSH and low T4 and T3 while people from the latter group have elevated TSH, but normal levels of T4 and T3.

The study confirmed the strong presence of anemia among hypothyroid patients. Not just that, but the frequency of anemia was similar in patients with both overt and subclinical hypothyroidism.

The prevalence of anemia in overt hypothyroidism group was 43% while 39% subjects with subclinical hypothyroidism were anemic. Compared to them, only 26% healthy controls had anemia.

Scientists concluded the study explaining that anemia of chronic disease is the most widespread form of anemia in hypothyroid patients[iv] (see common types of anemia in hypothyroid people below).

The reduced concentration of thyroid hormones has an adverse impact on erythropoiesis, production of red blood cells.

In turn, it paves the way for the development of anemia in hypothyroid patients. In a study carried out by Das C. et al frequency of anemia in subclinical and overt hypothyroidism subjects was 26.6% and 73.2% respectively.

The prevalence of anemia is much higher in persons with subclinical hypothyroidism than the general population.

Causes of anemia in hypothyroid patients are numerous including iron deficiency, insufficient stimulation of euthyroid colony development by thyroid hormones, reduced distribution of oxygen to tissues, among others[v].

Iron deficiency

Iron deficiency is a common cause of anemia and it has a lot to do with thyroid function, especially hypothyroidism.

Why does this happen?

The truth is that evidence on the underlying mechanisms of anemia in hypothyroid people is scarce and more studies are needed to investigate this subject. Multiple mechanisms play a role in iron deficiency in hypothyroid patients.

A growing body of evidence confirms that patients with hypothyroidism experience gastrointestinal dysfunctions[vi] such as low gastric acid secretion.

That being said, gastric acid plays a vital role in the absorption of minerals such as calcium, magnesium, zinc, and iron. In turn, underactive thyroid gland alters the absorption of nutrients thus causing deficiencies and iron deficiency is considered one of them.

Iron is vital for blood production and about 70% of the body’s iron is found in hemoglobin. However, an important component of hemoglobin called Heme I which is connected to TPO(thyroid peroxidase), this enzyme acts by releasing iodine to tyrosine for production of thyroid hormones.

Insufficient levels of iron lead to low hemoglobin and inadequate TPO binding. The consequence of this reaction is a major decrease in synthesis of thyroid hormones T4 and T3.

Due to the fact that thyroid hormone impairs the Heme oxidation rate in liver, decreased thyroid function paves the way for a series of chain reactions causing iron deficiency anemia.

Types of anemia in hypothyroid patients

While anemia is common in hypothyroid persons, it is important to understand that there are different types of anemia and not all cases are equal.

Below, you’re going to learn more about the most common forms of anemia in individuals with hypothyroidism.

Anemia of chronic disease

Anemia of chronic disease is the 2nd most frequent type of this condition, right after the iron deficiency. This particular form of anemia develops in people with either chronic or acute immune activation.

It is usually referred to as anemia of inflammation[vii] because it is linked to various chronic inflammatory conditions such as cancer, kidney disease, infection, and autoimmune diseases.

Speaking of autoimmune diseases it is important to mention that the most common cause of hypothyroidism in Americans is an autoimmune condition called Hashimoto’s thyroiditis.

Pernicious anemia

Pernicious anemia is defined as a condition wherein megaloblasts, forerunners of red blood cells, circulate in the blood, but don’t act as blood cells.

The condition is a result of disrupted uptake of vitamin B12 due to IF (intrinsic factor) in the gastric mucosa. Basically, your stomach doesn’t produce a factor that will improve absorption of vitamin B12 from the food you consume.

Pernicious anemia is classified as an autoimmune disease. As a result, the condition is common in autoimmune conditions such as Hashimoto’s thyroiditis, Graves’ disease (the most common cause of hyperthyroidism), and vitiligo (loss of skin pigmentation)[viii].

Vitamin B12 deficiency anemia

While pernicious anemia is associated with vitamin B12 deficiency it’s not the same thing as vitamin B12 deficiency anemia.

Confused?

Can’t blame you, this really is complicated. Vitamin B12 deficiency anemia indicates the body doesn’t have enough red blood cells due to an insufficient concentration of vitamin B12. Pernicious anemia is not the only cause of deficiency in this micronutrient and many other factors play a role.

These include insufficient intake of vitamin B12, gastric atrophy, parasites, among others. It is important to mention that vitamin B12 deficiency is common in persons with hypothyroidism[ix].

Iron deficiency anemia

Potential causes of iron deficiency anemia in hypothyroid patients are explained above, but it’s still important to address this condition.

Iron deficiency anemia is one of the most common forms of anemia that occurs due to insufficient intake of iron. This can be due to poor absorption of the mineral.

Women are at a higher risk of developing iron deficiency anemia which correlates with the prevalence of hypothyroidism, a condition that is also more common in females.

Folate deficiency anemia

Folate deficiency anemia is a condition that occurs when the body doesn’t have enough folate or vitamin B9, which is the natural form of folic acid found in foods. One of the most common causes of this type of anemia is an inadequate function of digestive system. As seen above, hypothyroid patients tend to experience gastrointestinal difficulties.

How is anemia categorized?

Anemia can occur due to a number of reasons and there are multiple types of this condition. We can categorize different forms of anemia into the following categories:

  • Microcytic anemia – refers to types of anemia where body’s tissues and organs don’t get enough oxygen to function properly. Anemia of chronic disease, iron deficiency anemia and other similar conditions fall into this category
  • Normocytic anemia – forms of anemia where the average concentration of hemoglobin is within normal limits. It is usually associated with chronic infections and chronic systemic diseases. A vast majority of normocytic anemias are a result of inadequate production of red blood cells, renal failure[x]
  • Macrocytic anemia – refers to types of anemia where red blood cells are larger than they should be. Causes of macrocytic anemia are numerous including hypothyroidism, liver disease, alcoholism, and other problems and health conditions[xi]

Treating anemia in hypothyroidism

When left unmanaged, anemia can cause different complications. It is important to be proactive about this problem. If you experience symptoms mentioned above, you should schedule an appointment to see your doctor who will diagnose the problem.

On the other hand, if you already have hypothyroidism make sure you see your doctor regularly, lab tests will show whether everything is okay with your blood.

Treatment of anemia in hypothyroid patients depends on the type of the condition and its causes. For example, in iron deficiency anemia a combination of levothyroxine and iron salt works best[xii]. While supplements are a popular tool to address anemia, you should consult your doctor before using those products.

Your doctor will inform you whether supplements are safe and effective, particularly if hypothyroidism in your case also caused gastrointestinal dysfunctions.

A common mistake that people make when managing anemia is to assume that iron deficiency is to blame when there different types of anemia and their causes differ.

Preventing anemia

A healthy lifestyle is important for hypothyroid patients, particularly if you want to prevent anemia and avoid complications it would cause.

Below, you can see practical tips and tricks that will help you prevent anemia or help you manage it:

  • Ditch unhealthy foods that have little to no nutritional value. These foods cannot supply your body with much-needed nutrients that are also important for red blood cells
  • Stay hydrated throughout the day. Drinking enough water is important for the function of the body’s tissues and organs, including digestive system. That way, the absorption of nutrients improves
  • Avoid drinking alcohol and excessive amounts of coffee which could impair digestion
  • Eat a well-balanced diet, don’t limit yourself to one food group only. Instead, make sure your diet consists of different types of food because all of them deliver different nutrients such as folic acid, iron, vitamin C, vitamin B12, and others
  • Avoid soda beverages, they are high in sugar and poor in nutrients thus blocking iron absorption

Conclusion

Anemia is a common condition that affects millions of people, primarily non-pregnant women. This condition is common in patients with hypothyroidism, but it can be managed.

Adequate management depends on the type of anemia, but a healthy lifestyle is important to prevent it and avoid consequences it could cause.

References

[i] Le CHH. The Prevalence of Anemia and Moderate-Severe Anemia in the US Population (NHANES 2003-2012). Collins JF, ed. PLoS ONE. 2016;11(11):e0166635. doi:10.1371/journal.pone.0166635. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5112924/

[ii] Global anemia prevalence and number of individuals affected, World Health Organization http://www.who.int/vmnis/anaemia/prevalence/summary/anaemia_data_status_t2/en/

[iii] Anemia, Mayo Clinic https://www.mayoclinic.org/diseases-conditions/anemia/symptoms-causes/syc-20351360

[iv] Erdogan M, Kosenli A, Ganidagli S, Kulaksizoglu M. Characteristics of anemia in subclinical and overt hypothyroid patients. Endocrine Journal 2012 Dec;59(3):213-20. https://www.ncbi.nlm.nih.gov/pubmed/22200582

[v] Das C, Sahana PK, Sengupta N, Giri D, Roy M, Mukhopadhyay P. Etiology of anemia in primary hypothyroid subjects in a tertiary care center in Eastern India. Indian Journal of Endocrinology and Metabolism. 2012;16(Suppl 2):S361-S363. doi:10.4103/2230-8210.104093. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3603077/

[vi] Yaylali O, Kirac S, Yilmaz M, et al. Does Hypothyroidism Affect Gastrointestinal Motility? Gastroenterology Research and Practice. 2009;2009:529802. doi:10.1155/2009/529802. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2833301/

[vii] Anemia of chronic disease, New England Journal of Medicine http://www.nejm.org/doi/full/10.1056/NEJMra041809

[viii] Pernicious anemia and vitamin B12 deficiency, MedicineNet https://www.medicinenet.com/pernicious_anemia/article.htm#pernicious_anemia_facts

[ix] Jabbar A, Yawar A, Waseem S, et al. Vitamin B12 deficiency common in primary hypothyroidism. Journal of the Pakistan Medical Association 2008 May;58(5):258-61. https://www.ncbi.nlm.nih.gov/pubmed/18655403

[x] Normocytic normochromic anemias, Britannica https://www.britannica.com/science/blood-disease/Normocytic-normochromic-anemias#ref249458

[xi] Macrocytic anemia, Healthline https://www.healthline.com/health/macrocytic-anemia

[xii] Ravanbod M, Asadipooya K, Kalantarhormozi M, et al. Treatment of iron-deficiency anemia in patients with subclinical hypothyroidism. American Journal of Medicine 2013 May;126(5):420-4. Doi: 10.1016/j.amjmed.2012.12.009 https://www.ncbi.nlm.nih.gov/pubmed/23582934

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