Hypothyroidism Facts and Statistics: What You Need to Know

Hypothyroidism (low thyroid function) is a common hormonal condition. One in 300 people in the United States is diagnosed with hypothyroidism. Females and people over age 65 are the groups most often diagnosed with hypothyroidism. While there is no cure, treatment can restore hormone levels and reduce symptoms.

This article will explore important facts and statistics about hypothyroidism, including how common it is; who it affects by race, sex, and age; its causes and risk factors; screening and early detection; and mortality.

Healthcare provider performing an ultrasound scan of a person's thyroid

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Hypothyroidism Overview

Hypothyroidism is a condition in which the thyroid gland (located at the front of the neck) does not produce enough thyroid hormones. Thyroid hormones are responsible for the body’s metabolism (the way it uses energy) and major functions (such as heart rate).

Without enough thyroid hormones, the body’s functions slow down, causing a variety of symptoms. While symptoms vary from person to person, common symptoms of hypothyroidism include:

  • Fatigue
  • Weight gain
  • Cold intolerance
  • Muscle and joint pain
  • Thinning hair
  • Slowed heart rate
  • Depression
  • Heavy or irregular menstrual periods or infertility

How Common Is Hypothyroidism?

Hypothyroidism is a common endocrine (hormonal) disorder. In the United States, 1 in 300 people have been diagnosed with hypothyroidism.

Rates of hypothyroidism have been increasing in recent years. Levothyroxine, the most commonly used treatment for hypothyroidism, is one of the most prescribed drugs in the United States.

More than 12% of the U.S. population will develop a thyroid condition at some point during their lifetime.

Hypothyroidism by Ethnicity

Studies on the incidence of hypothyroidism in different ethnicities is limited, however, it has been established that White people are more likely to be diagnosed with hypothyroidism than other ethnicities.

In one Brazilian study, nearly 17 out of 100 White women vs. nearly 7 out of 100 Black women were diagnosed with hypothyroidism.

Hypothyroidism by Age and Gender

Hypothyroidism is 8 to 9 times more likely to develop in women than men. The risk of developing hypothyroidism increases in people who are pregnant, have recently given birth, or are going through menopause.

As people age, the risk of developing hypothyroidism increases as well. Hypothyroidism is more prevalent in people over 60.

Causes of Hypothyroidism and Risk Factors

Hashimoto’s disease, an autoimmune disease that affects the thyroid, is the most common cause of hypothyroidism. In underdeveloped countries, iodine insufficiency is another common cause.  

People who have experienced the following may be more likely to develop hypothyroidism:

  • A previous thyroid problem, such as a goiter (an enlarged thyroid gland)
  • Surgery or radioactive iodine treatment to correct a thyroid problem
  • Family history of thyroid disease
  • Pregnancy within the past six months
  • Radiation treatment to the neck or chest
  • Turner syndrome (a chromosomal condition present at birth)

An individual may also be more at risk for an underactive thyroid if they have other health problems such as:

  • Type 1 or type 2 diabetes (inability to control blood sugar)
  • Lupus (a chronic autoimmune inflammatory disease)
  • Celiac disease (a condition in which gluten triggers immune system damage to the small intestine)
  • Rheumatoid arthritis (an autoimmune condition affecting the joints and other tissues)
  • Pernicious anemia (an autoimmune condition in which the body does not absorb vitamin B12 correctly)
  • Sjögren’s syndrome (an autoimmune disease that attacks the cells producing saliva and tears)

What Are the Mortality Rates for Hypothyroidism?

People who are being successfully treated for hypothyroidism can expect to reach a normal life expectancy.

However, women with hypothyroidism may be at increased risk of death from other diseases such as cardiovascular disease, diabetes, and cerebrovascular diseases such as blood clots or artery blockages.

People with long-term untreated and severe hypothyroidism may experience a rare condition known as myxedema coma. Myxedema coma causes a slowed heart rate, altered mental state, and hypothermia (low body temperature) and can lead to death if not treated promptly.

Screening and Early Detection

The U.S. Preventive Services Task Force (USPSTF) does not recommend screening people who are not pregnant and do not have symptoms of hypothyroidism. Newborns are routinely screened for hypothyroidism soon after birth.

The American Thyroid Association recommends clinical evaluation for risk factors and symptoms of thyroid disease for all people seeking to become pregnant or are newly pregnant, and then performing a blood test if they are at higher risk.

In any person, a healthcare provider will take a medical history and conduct a physical exam if hypothyroidism is suspected. Because the symptoms of hypothyroidism are often vague and overlap with other diseases, diagnosis requires blood tests to measure thyroid stimulating hormone (TSH) and other thyroid hormones such as T3 and T4.

Routine blood tests to analyze thyroid function can help lead to early detection of a low-functioning thyroid. Early treatment for hypothyroidism can normalize thyroid hormone levels and prevent further damage to organs such as the heart.

Summary

Hypothyroidism is a chronic condition that occurs when the thyroid gland does not produce enough thyroid hormones. White women, people over age 60, and those with underlying health conditions, such as rheumatoid arthritis and previous damage to the thyroid, are more likely to develop the disease.

Early detection via blood tests to check thyroid hormone levels can improve diagnosis, speed up treatment, and decrease mortality.

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