About 20 million Americans have some form of thyroid disease, according to the American Thyroid Association. That is roughly 6% of the population. The striking part is that up to 60% of those people do not know they have it. Thyroid problems are among the most common endocrine conditions in the country, and they are also among the most frequently missed.
How Many People Have Thyroid Issues In The U S?
Roughly 20 million people in the United States have a thyroid disorder of some kind. That number comes from the American Thyroid Association and is the figure most often cited in clinical literature.
To put it in perspective, that is more people than live in the entire state of New York. Women are affected far more often than men. Some estimates suggest women are five to eight times more likely to develop a thyroid problem. The risk also climbs with age, and a family history of thyroid disease raises it further.
The 20 million figure includes all thyroid conditions — hypothyroidism, hyperthyroidism, thyroid nodules, goiter, thyroid cancer, and autoimmune thyroid diseases like Hashimoto’s and Graves’ disease. It is not a count of any single condition.
One detail that gets lost in the headline number: the American Thyroid Association estimates that around 12% of the U.S. population will develop a thyroid condition at some point in their lifetime. That is a much larger share than the 6% who have one right now.
What Is the Difference Between Hypothyroidism and Hyperthyroidism?
Hypothyroidism means the thyroid gland does not make enough thyroid hormone. Hyperthyroidism means it makes too much. They are opposite problems with different symptoms, different causes, and different treatments.
The thyroid is a small butterfly-shaped gland at the front of your neck. It releases hormones — mainly T4 and T3 — that control how fast your cells use energy. When that signal is too low or too high, almost every system in the body feels it.
In hypothyroidism, metabolism slows. Common symptoms include fatigue, weight gain, cold intolerance, constipation, dry skin, and slowed thinking. In the U.S., the most common cause is Hashimoto’s disease, an autoimmune condition where the immune system attacks the thyroid.
In hyperthyroidism, metabolism speeds up. Symptoms often include weight loss despite normal eating, rapid heartbeat, heat intolerance, anxiety, tremors, and trouble sleeping. Graves’ disease, also autoimmune, is the most common cause in the U.S.
Hypothyroidism is far more common than hyperthyroidism. When researchers estimate the total burden of thyroid disease, most of that 20 million is hypothyroidism and its milder form, subclinical hypothyroidism.
Why Do So Many Cases Go Undiagnosed?
Thyroid symptoms are easy to blame on something else. Fatigue, weight changes, mood shifts, and trouble concentrating are also signs of stress, poor sleep, depression, perimenopause, and normal aging. That overlap is the main reason so many cases are missed.
The symptoms also build slowly. A thyroid that gradually produces less hormone over months or years does not announce itself. People adapt to feeling a little more tired, a little colder, a little foggy, and assume that is just how they feel now.
There is a second factor. Some clinicians do not routinely screen for thyroid disease in adults who have no symptoms. Major guidelines differ on this point. The U.S. Preventive Services Task Force has concluded that the evidence is insufficient to recommend screening for thyroid dysfunction in adults who are not pregnant and have no symptoms. That is a statement about evidence, not a claim that screening is harmful.
When symptoms are present, testing is a different matter. A simple blood test can measure thyroid-stimulating hormone (TSH), which is the standard first test. If TSH is abnormal, clinicians usually follow up with free T4 or T3.
Who Is Most at Risk for Thyroid Disease?
Women, older adults, and people with a family history of thyroid disease carry the highest risk. Autoimmune thyroid conditions also cluster with other autoimmune diseases, so a personal history of type 1 diabetes, celiac disease, or rheumatoid arthritis raises the odds.
Several other factors are well established:
- Being female — thyroid disease is far more common in women
- Age over 60
- A family history of thyroid disease or autoimmune conditions
- Prior radiation to the head or neck
- Certain medications, including lithium and some heart rhythm drugs
- Pregnancy and the postpartum period
- Iodine deficiency or, less commonly in the U.S., iodine excess
Iodine deserves a note. The thyroid needs iodine to make hormone. In the U.S., iodized salt and fortified foods have largely eliminated severe iodine deficiency, which is why the causes here look different from regions of the world where deficiency is still common.
Pregnancy is a distinct situation. Thyroid changes during pregnancy are common, and untreated thyroid disease can affect both mother and baby. This is one area where screening recommendations differ from the general adult population, and pregnant women should follow guidance from their obstetric provider.
How Common Is Thyroid Disease Compared With Other Conditions?
Thyroid disease sits in the same range as some of the most familiar chronic conditions in the country. It is less common than diabetes but more common than many people assume.
Here is a rough comparison using widely cited national estimates. These are approximate figures meant to show scale, not exact counts.
| Condition | Approx. U.S. Prevalence |
|---|---|
| Any thyroid disease | About 20 million people |
| Diagnosed diabetes | Roughly 30 million adults |
| Heart disease | Tens of millions of adults |
| Thyroid cancer (new cases per year) | Tens of thousands |
The comparison matters because thyroid disease gets far less public attention than its numbers would suggest. A condition affecting 20 million people is not rare by any definition.
Is Thyroid Disease Getting More Common?
Some types appear to be rising, but the picture is more complicated than a simple increase. The clearest trend is in thyroid cancer diagnoses.
Thyroid cancer incidence in the U.S. rose sharply for several decades. Most researchers attribute a large share of that rise to better detection — more imaging tests and biopsies finding small cancers that would previously have gone unnoticed. Whether the true underlying rate is also rising is still debated. Some evidence points to a real increase in more advanced cases, which suggests detection alone may not explain everything.
For hypothyroidism and hyperthyroidism, the data are less clear. Better testing and greater awareness mean more cases are being identified than in past decades. That alone can look like a rise even if the underlying rate is stable.
Autoimmune thyroid disease is genuinely influenced by genetics and environment, and researchers continue to study whether factors like diet, stress, and chemical exposures play a role. The evidence here is not settled.
What Should You Do With This Information?
The most useful takeaway is not the exact number. It is that thyroid disease is common, frequently silent, and easy to test for.
If you have persistent symptoms that fit the patterns described here — ongoing fatigue, unexplained weight change, temperature intolerance, or a visible swelling at the base of your neck — that is a reasonable reason to talk with a clinician about testing. A TSH blood test is straightforward and widely available.
If you have no symptoms, the guidance is less certain. Major preventive health bodies do not currently recommend routine thyroid screening for adults without symptoms, because the evidence that it improves outcomes is not strong enough to support it. That is an honest statement of where the science stands, not a reason to avoid testing if you have concerns.
What is not in question is the scale. Twenty million Americans, most of them unaware. That is the number worth remembering.
Frequently Asked Questions
How many people in the US have thyroid disease?
About 20 million Americans have some form of thyroid disease, according to the American Thyroid Association. That is roughly 6% of the population, and up to 60% of them do not know they have it.
What percentage of the population has thyroid problems?
Around 6% of Americans currently have a thyroid condition. The American Thyroid Association estimates that about 12% will develop one at some point in their lifetime.
Are thyroid problems more common in women?
Yes. Women are several times more likely than men to develop thyroid disease, and risk rises with age. A family history of thyroid or autoimmune disease increases it further.
Can you have thyroid disease and not know it?
Yes. Up to 60% of people with thyroid disease are unaware of it, largely because symptoms like fatigue and weight change overlap with many other conditions. A simple blood test can detect it.
