How Common Is Hashimoto’s Disease?

Also called chronic lymphocytic thyroiditis or Hashimoto’s thyroiditis, Hashimoto’s disease is an organ-specific autoimmune disorder that often causes hypothyroidism (underactive thyroid).

The thyroid gland is a butterfly-shaped organ in your neck that produces two critical hormones called T3 and T4. These two hormones are responsible for helping cells metabolize proteins, vitamins, and nutrients.

The thyroid works with the pituitary gland (a pea-sized gland in your brain) to carefully maintain the correct level of thyroid hormones in your bloodstream.

People with Hashimoto’s disease produce thyroid antigens, which may cause white blood cells to attack the thyroid. This leads to lower thyroid hormone levels in the blood. In some people with Hashimoto’s disease, thickening and scarring (fibrosis) cause the thyroid to become too damaged to function.

What does Hashimoto's disease do to your body?

A healthy thyroid is a very well-regulated organ. A complex web of communication between cells helps maintain ideal levels of thyroid hormones in most people.

The pituitary gland communicates with the hypothalamus to release thyroid-stimulating hormone (TSH). This hormone tells the thyroid to produce more (or less) T3 and T4 hormones depending on how much your body needs to function.

Cells in your body use thyroid hormones to break down proteins, glucose, fat, and every other vitamin and mineral you consume. It’s normal for your body to use around 5%¹ of your total thyroid hormones each day. Excess hormones are broken down in the liver, muscles, kidneys, and central nervous system.

People with Hashimoto’s disease develop thyroid antigens that cause the T-cells to attack various structures in the thyroid, eventually leading to hardening, scarring, and even destruction of the thyroid.

Many Hashimoto’s disease cases are subclinical, meaning they are asymptomatic. In these cases, thyroid antigens are present in the blood, but they do not cause hyperthyroidism.

Hashimoto’s disease symptoms

Hashimoto’s disease is a progressive disease where the immune system damages your thyroid over time, causing a variety of symptoms.

The most common Hashimoto’s disease symptoms include:

• Fatigue or sluggishness

• Weight gain

• Joint pain

• Muscle pain

• Diarrhea

• Constipation

• Temperature intolerance

• Slow heart rate (also called bradycardia)

• Brittle or thinning hair

• Irregular or heavy menstrual periods

• Fertility issues

• Dry skin

• High blood pressure

• Lack of coordination (also called ataxia)

• An enlarged tongue (also called macroglossia)

Early Hashimoto’s disease can cause hyperthyroidism symptoms in rare cases, including:

• Weight loss

• Sweating

• Nervousness

• Anxiety

• Irritability

• Irregular heartbeat (also called an arrhythmia)

• Rapid heart rate (also called tachycardia)

• Skin thinning

• Sweating

• Difficulty sleeping

Many other diseases share these symptoms, so you should discuss any changes to how you feel with your doctor.

Seek emergency medical assistance if you are experiencing symptoms like rapid heart rate, irregular heart rate, or extremely high blood pressure.

Types of Hashimoto’s disease

Your symptoms may depend on the type of Hashimoto’s disease you have. There are four main types of Hashimoto’s, including:

Fibrous

The thyroid is extensively damaged in the fibrous variant of Hashimoto’s disease, causing a buildup of tough scar tissue. This causes the thyroid to enlarge (goiter) and significantly reduces thyroid hormone levels.

People with this variant nearly always have clinical symptoms. Around 10–13%² of Hashimoto's disease cases are fibrous.

Fibrous atrophy

The thyroid is also destroyed and replaced with fibrous tissue in this Hashimoto’s disease variant, but the thyroid shrinks in response to the damage. You will likely experience symptoms with this type of Hashimoto’s.

Riedel’s thyroiditis

The thyroid is severely damaged by T-cells in Riedel’s thyroiditis cases, and the damage extends beyond the thyroid and into other structures in the neck.

This disease sometimes mimics another condition called multifocal fibrosclerosis, which causes fibrous damage to various structures throughout your body.

IgG4 thyroiditis

Extensive damage to the thyroid and extending structures can be expected in IgG4 thyroiditis cases. IgG4-positive plasma cells are one of the causes of the damage.

This disease can be confused with malignant lesions.

How common is Hashimoto’s disease?

The estimated annual incidence of Hashimoto’s disease is 0.3 to 1.5 cases³ per 1,000 people, and the incidence rate in the US is around 2%.⁴ The condition is ten times⁴ more common in women than in men. 

Researchers don’t know if Hashimoto’s disease is becoming more common, or if medical advancements have made it easier to detect.

It is challenging to determine how many people are impacted by Hashimoto’s disease worldwide. The disease is the most common cause of hypothyroidism in developed countries. Other causes include congenital hypothyroidism, thyroiditis (inflammation of the thyroid), medicines, other autoimmune disorders, or rare genetic conditions like amyloidosis.

The leading cause of thyroid issues in underdeveloped countries is a lack of iodine from dietary sources.

Hashimoto’s disease often runs in families, and there’s up to a 50%⁵ chance your siblings or parents also have the condition if you have it. Hashimoto’s disease is often clustered in families and communities for this reason.

Certain gene clusters are thought to contribute to Hashimoto’s disease. These clusters are more common among white people.⁶ However, people of any race or ethnicity can develop Hashimoto’s disease.

Who is most likely to develop Hashimoto’s disease

Researchers believe Hashimoto’s is more likely to affect you if you:

• Are aged between 30 and 50

• Are female

• Over-consume salt, seaweed, cranberry juice, or other dietary sources of iodine

• Take iodine supplements (including prenatal vitamins)

• Have a family history of Hashimoto’s disease or other thyroid autoimmune disorders

• Have an existing autoimmune disorder⁷ such as celiac disease, Graves’ disease, rheumatoid arthritis, and multiple sclerosis

• Have received anti-cancer drugs (e.g., cytotoxic chemotherapy or immunotherapy)

• Work around environmental toxins or heavy metals

• Live in a country without iodized salt requirements

Most people don’t develop Hashimoto’s disease, even though they have at least one of these risk factors. Having one or more risk factors does not mean you will develop Hashimoto’s disease.

What are the risk factors for Hashimoto’s disease?

Hashimoto’s disease is thought to be caused by both genetic and environmental factors.

You likely have a genetic predisposition to hypothyroidism if you have Hashimoto’s disease, but the condition might be triggered by environmental factors.

In other words, some people with a higher risk of Hashimoto’s because of genetics may never develop the disease. In other cases, Hashimoto’s disease is triggered by an environmental factor that activates their genetic predisposition to the disease.

Environmental risk factors thought to contribute to Hashimoto’s disease include:

Excessive iodine consumption

Salt is iodized in many countries to prevent iodine deficiencies, but this has led some people to consume more iodine than recommended.

Over-consuming iodine is a significant risk factor for Hashimoto’s disease. Consuming too much salt combined with other dietary sources of iodine (e.g., seaweed, processed bread, snacks, and cranberry juice) can increase your risk of overconsumption.

Daily multivitamins may also cause you to consume too much iodine. For example, iodine-rich prenatal vitamins⁸ have been linked to congenital hypothyroidism in children.

Environmental toxins (chemicals)

Certain environmental chemicals have been linked to Hashimoto’s disease, including polychlorinated biphenyls (PCBs),⁹ bisphenol A, brominated flame retardants, and perfluorinated chemicals.

These chemicals are used in a variety of manufacturing processes, including plastic and food production. The use of PCBs (mostly used for coolants and lubricants) in manufacturing is now illegal, but their longevity means many pieces of electrical equipment made before the 1970s still contain them.

Environmental toxins (heavy metals)

Various carcinogenic heavy metals¹⁰ are linked to thyroid disorders, including cadmium (Cd) and manganese (Mn).

Incidences of Hashimoto’s disease, Graves’ disease, and thyroid cancer are higher in areas with high volcanic activity. Many researchers believe heavy metal combinations in the air (caused by volcanic activity) are to blame. The link between metals and thyroid disorders is still an area of ongoing study.¹¹

Certain viruses

Several conditions have been linked¹² to Hashimoto’s disease. These include mumps, Epstein Barr, hepatitis C, parvovirus B19, herpes, rubella, retroviruses, HIV, and human T-cell lymphotropic virus-1. These viruses activate the immune system and may trigger Hashimoto’s disease genetics.

Medications

Many cytotoxic medications and immunotherapy regimens used to treat cancer are associated with Hashimoto’s disease.¹³ Examples include cytotoxic chemotherapy regimens, tyrosine kinase inhibitors, and lenalidomide.

Vitamin deficiencies

There are links¹⁴ between vitamin D deficiency and Hashimoto’s disease, but researchers still don’t know whether vitamin D deficiency leads to Hashimoto’s disease or vice versa.

If you have any of these risk factors, you’re not guaranteed to develop Hashimoto’s disease. No risk factor is thought to cause Hashimoto’s disease alone. Those who develop autoimmune disorders are thought to already have a genetic predisposition, and these risk factors act as triggers.

Can you lower your risk of developing Hashimoto’s disease?

There is no known way to prevent Hashimoto’s disease.

Like other autoimmune disorders, a complex combination of genetic and environmental factors plays a role in the condition’s development. Avoiding the known environmental risk factors of Hashimoto’s disease may decrease your risk, but many people develop Hashimoto’s disease for unknown and unrelated reasons.

Genetics are complex and can skip generations, so you can have a predisposition to Hashimoto’s disease without having a direct family member with the disorder.

Hashimoto’s disease cannot be cured, but the symptoms are manageable and effective treatment can reduce the risk of long-term health complications.

Hashimoto’s disease complications

Many people with Hashimoto’s disease never develop symptoms or complications. However, the condition can sometimes lead to hypothyroidism, which can cause several complications⁴ if left untreated, including:

• High blood pressure

• High cholesterol

• Heart disease

• Heart failure

• Myxedema (a rare condition that can lead to coma)

• Lymphoma

Only a small percentage of people with Hashimoto’s disease develop complications, and many can be successfully treated with standard treatments.

If you are worried about these complications, discuss them with your doctor.

How is Hashimoto’s disease treated?

Hashimoto's disease can be effectively treated with thyroid hormone replacement medication.

Modern synthetic hormones (levothyroxine sodium) like Synthroid, Levoxyl Tirosint, Levo-T, and Unithroid are used to stabilize thyroid hormone levels in the blood. These synthetic hormones are carefully constructed to mimic human thyroid hormones.

Some people with Hashimoto’s disease may need to take replacement hormones for the rest of their lives to keep their thyroid hormone levels stable.

Your doctor will work out the right dosage for you based on your age, weight, gender, height, and blood levels. Synthetic hormones are usually taken once daily in pill form.

Non-synthetic hormones extracted from animals used to be a common Hashimoto’s treatment, but these aren’t as effective as synthetic hormones, which are now preferred. Thyroid extract is still available, but you shouldn’t take it unsupervised. It’s always best to follow your doctor’s advice.

What is the prognosis?

Hashimoto’s disease has a good prognosis, and most people have a normal life expectancy. Modern treatments can effectively reduce symptoms and minimize long-term hypothyroidism complications.

Complications from untreated Hashimoto’s disease or secondary cancers can occur, but rarely. You can discuss any questions or concerns about your prognosis with your doctor.

Does Hashimoto’s disease need to be treated?

Some people will require treatment at some point because their system has damaged their thyroid enough to cause clinical symptoms and disrupt hormone levels. However, this may not happen for many years.

Even with a diagnosis, you might never experience any clinical symptoms of Hashimoto’s disease. Your doctor will recommend a treatment option if they think it’s needed, but this might not be until you have symptoms. Some people require more immediate treatment.

What about natural remedies?

Research¹⁵ suggests gluten-free, whole-food, or anti-inflammatory¹⁶ diets can reduce Hashimoto’s disease symptoms.

Some early studies also suggest vitamins and minerals like selenium,¹⁷ vitamin D,¹⁸ and zinc¹⁹ play a role in balancing your thyroid hormones.

Taking supplements or changing your diet may reduce symptoms, but most people still need to take synthetic thyroid hormones.

Some diets and vitamins may interact with other medications, so you should always discuss any dietary supplements with your doctor before taking them.

When to see a doctor about Hashimoto’s disease

You should see a doctor if you are experiencing any Hashimoto’s disease symptoms, even though having symptoms doesn’t guarantee you have the condition. Hashimoto’s disease has the same symptoms as various common illnesses and conditions.

Discuss Hashimoto’s with your doctor if other members of your family have the condition, as you may need to undergo additional testing.

Many people with Hashimoto’s disease try multiple treatments and receive different diagnoses before they find out what is causing their symptoms. If your doctor suspects thyroid issues are causing your symptoms, they can order blood tests such as a thyroid antigen test or a thyroid function test.

The lowdown

Around 2% of people in the US have Hashimoto’s disease, a thyroid autoimmune disorder where the immune system attacks and damages the thyroid gland. This often causes your thyroid to underproduce thyroid hormones.

Some people with Hashimoto’s disease never develop clinical symptoms, while others have symptoms such as a low heart rate, heat sensitivity, fatigue, joint pain, or high blood pressure.

There are no known strategies for preventing Hashimoto’s disease, but consciously avoiding environmental triggers may stop the disease from manifesting if you have a genetic predisposition to it.

Hashimoto’s is more common in women, people in the 30–50 age group, and people with a family history of thyroid disorders.

Modern synthetic thyroid hormones can help stabilize thyroid hormone levels in your blood, so the prognosis is usually positive.

Early diagnosis and effective treatment can prevent the long-term complications of hypothyroidism, so speak to your doctor if you think you have symptoms.