Thyroid Disease Facts and Statistics: What You Need to Know

More than 12% of people in the United States will develop thyroid disease at some point in their lifetime. Millions of Americans are already living with it, and many may not even know it.1

The two main types of thyroid conditions are:
• Underactive thyroid (hypothyroidism
• Overactive thyroid (hyperthyroidism
This article reviews facts and statistics to help you understand thyroid disease and its impact.
Thyroid Disease Overview
The thyroid is a butterfly-shaped gland in the front of your throat. Through the production and release of thyroid hormones, it regulates many automatic processes in your body. These include:3
• Breathing
• Heart rate
• Digestion
• Energy production
• Muscle strength
• Body temperature
• Weight
• Mood
• Menstrual cycles
Hypothyroidism
In hypothyroidism, your thyroid gland doesn’t make enough thyroid hormone. This slows down your metabolism and causes:4
• Fatigue
• Weight gain
• Trouble tolerating cold
• Joint and muscle pain
• Dry skin and hair
• Temporary hair loss
• Heavy or irregular menstrual periods
• Fertility problems dealing with female reproduction
• Slowed heart rate
• Goiter (an enlarged thyroid that feels like a lump in your throat)
Some cases of hypothyroidism are caused by an autoimmune condition called Hashimoto’s
disease.
Hyperthyroidism
In hyperthyroidism, your thyroid produces too much thyroid hormone. This speeds up many of your body’s processes. Symptoms include:3
• Nervousness or irritability
• Fatigue
• Muscle weakness
• Trouble tolerating heat
• Insomnia
• Tremor
• Rapid, irregular heart rate
• Frequent bowel movements and/or diarrhea
• Weight loss
• Mood swings
• Goiter
Some cases of hyperthyroidism are caused by an autoimmune disorder called Graves’ disease. It can also be caused by thyroiditis (inflamed thyroid gland), growths called thyroid nodules, and too much iodine in the blood. Thyroid hormone production relies on iodine.
How Common Is Thyroid Disease?
Thyroid disease is fairly common. An estimated 20 million people in the United States have thyroid disease. As many as 60% of people with thyroid disease are not aware that they have it.1
Hypothyroidism is about 7.5 times more common than hyperthyroidism.5 In addition, experts estimate that thyroid disease is becoming more common.
Thyroid Disease by Ethnicity
The rates of autoimmune thyroid diseases are different among ethnic groups.
Hashimoto’s disease appears to be more common in White Americans and less common in Black Americans, Asian Americans, and Pacific Islanders.7
Graves’ disease appears to be more common in Americans who are Black and Pacific Islander. It is less common in people who are White.7
Thyroid Disease by Age and Sex
Rates of thyroid disease vary based on age and sex.8
Thyroid disease becomes more common as people age. Hypothyroidism is most often diagnosed between the ages of 30 and 50. Hyperthyroidism diagnoses are most common between ages 20 and 40.5
Thyroid disease is significantly more common in women.
Causes of Thyroid Disease and Risk Factors
Causes of hypothyroidism include:13
• Autoimmunity (most common in the United States)
• Iodine deficiency (rare in the United States but quite common worldwide)
• Radiation therapy for head and neck cancers
• Pregnancy
• Birth defect in the thyroid gland
Causes of hyperthyroidism include:3
• Autoimmunity
• Excess iodine
• Thyroid nodules
• Thyroiditis
• Noncancerous tumors on the pituitary gland, which is involved in thyroid function