An autoimmune disorder is when the body's immune system attacks one of its own body parts. There are autoimmune disorders for nearly every part of the body.
The thyroid gland, responsible for producing hormones that help regulate your body's basal metabolic rate, can be affected by two different autoimmune disorders: Hashimoto's disease and Graves' disease.
In this article, you'll learn what these two diseases are and how they differ.
Hashimoto's disease turns your immune system into an enemy. It targets your thyroid gland, weakening it and causing hypothyroidism — a condition where the thyroid is underactive. Hashimoto's disease is one of the many possible causes of hypothyroidism.
There are several groups of people who are more likely to get Hashimoto's disease than others.¹ In addition, some environmental conditions may increase a person's chances of getting the disease.
Having a family member with Hashimoto's disease increases one's likelihood of getting it. Several genes have been identified as increasing the risk factors for the disease.²
Women are significantly more likely to get Hashimoto's disease than men.³
Hashimoto's disease affects people between 30 and 50 more often than young people.⁴
Other autoimmune disorders
Those who have other autoimmune disorders, such as celiac disease, lupus, rheumatoid arthritis, Sjögren's syndrome, and type 1 diabetes, are also at a greater risk of getting Hashimoto's.
Exposure to radiation
One environmental risk factor for Hashimoto's is radiation exposure.⁵ The exposure can come from catastrophic events such as nuclear fallout and more common radiation sources, such as radiation from medical devices.
Bacterial or viral infections
Certain infections increase a person's chances of developing Hashimoto's. These include viral infections such as hepatitis C and bacterial infections such as Helicobacter pylori.⁶
Overconsumption of iodine
Because iodine plays a key role in thyroid function, those with excessive iodine intake are more likely to get Hashimoto's disease. One study showed that subjects in an area with iodine deficiency were less likely than those with sufficient iodine intake to develop Hashimoto's.²
Aside from several symptoms, the most severe complication of hypothyroidism is myxedema coma.
Myxedema coma occurs when hypothyroidism gets so bad the body's functions slow down so much it becomes life-threatening. The condition doesn't necessarily mean the person becomes comatose, but extreme fatigue and lethargy are common and require immediate medical attention.
Now let's look at the difference between Graves' disease and Hashimoto's. Like Hashimoto's disease, Graves' is also an autoimmune disorder affecting the thyroid. The difference between the two is the type of antibodies your immune system attacks the thyroid with and how the attack impacts the thyroid.
Hashimoto's disease causes hypothyroidism, whereas Graves' disease causes hyperthyroidism. Since hyperthyroidism is a thyroid that produces too much of its hormones, Graves' disease is the opposite of Hashimoto's.
Although both diseases affect the thyroid differently, you'll notice as you look over the list of risk factors that there are a lot of similarities between the two conditions.
Genetic factors also play a role in your risk of Graves' disease. A family history of either Graves' or Hashimoto’s increases the chances that you'll develop the condition.
Like Hashimoto's disease, women are more likely to develop Graves' disease than men.⁷
While Hashimoto's is more likely among people aged 30–50, Graves' is slightly less discerning, affecting people at any age over 30 with greater frequency.⁸
Other autoimmune disorders
Graves' disease has its own list of autoimmune diseases that put someone at risk of having it. These include vitiligo, autoimmune gastritis, type 1 diabetes, and rheumatoid arthritis.
Nicotine from smoking cigarettes or other tobacco-based products significantly impacts thyroid health, putting you at greater risk for Graves' disease.⁹
Graves' disease may first appear during pregnancy.¹⁰
Similar to Hashimoto's disease, the complications from Graves' disease occur primarily as a result of the hyperthyroidism that it causes. Several possible complications can arise from having too much thyroid hormone in your blood, including:¹¹
Graves' orbitopathy occurs when the same antibodies that attack the thyroid attack parts of the eye. It results in retracted upper eyelids, bulging eyes, redness, and swelling.
This is the most common complication of Graves' disease, occurring in almost 25% of diagnosed patients.
Mild cases of the condition will go away on their own and are treated primarily by making the eye more comfortable.
In much the same way that antibodies in the immune system can attack the eyes and the thyroid, they can also attack parts of the skin. The skin can become thickened, inflamed, itchy, and painful.
This condition, called Graves' dermopathy, is much rarer than Graves' orbitopathy.
This complication is rare but life-threatening. Like how myxedema coma can turn hypothyroidism into a dangerous situation, a thyroid storm occurs when there is a sudden and dramatic increase of thyroid hormones in the body.
It’s associated with fever, tremors, nausea, vomiting, diarrhea, restlessness, and delirium. Thyroid storms require immediate medical attention.
The thyroid hormones have several biochemical reactions in the heart, so hyperthyroidism can worsen heart abnormalities.
People with hyperthyroidism are more likely to experience mitral valve prolapse, congestive heart failure for those at risk, and worsening angina. These conditions are often reversible when hyperthyroidism is caught early enough.
Generally speaking, Graves' disease will present itself through the symptoms of the resulting hyperthyroidism and Hashimoto's through the symptoms of hypothyroidism. However, early in the development of Hashimoto's, the thyroid may produce more hormones than usual, meaning that hyperthyroidism symptoms may also indicate both diseases.
Hypothyroidism (underactive thyroid)
Symptoms of hypothyroidism present themselves differently from one person to the next. In some cases, the symptoms of underactive thyroid are the direct opposite of overactive thyroid symptoms.
Intolerance to cold
Unexplained weight gain
Decreased heart rate
Pain in the joints or muscles
Irregular menstrual periods
Hyperthyroidism (overactive thyroid)
Hyperthyroidism symptoms vary from person to person.¹² Below is a list of common symptoms, though you are unlikely to experience all of them.
Unexplained weight loss
Intolerance to heat or unusual sweating
An increase in heart rate or an irregular heartbeat
Muscle weakness or shakiness
Increased bowel movement frequency
Irregular growth of the thyroid gland, known as goiter
Nervousness or irritability
Older people may also display symptoms not experienced by younger ones, such as lack of appetite.
Because both Graves’ disease and Hashimoto’s affect the thyroid and are difficult to diagnose based on symptoms alone, the procedure for confirming a diagnosis is similar.
If you suspect you have either autoimmune disease, the doctor will likely perform the following set of tests:
A thyroid that isn't functioning correctly can leave physical evidence of the problem, usually in the form of a goiter. A goiter is simply the medical term for an enlarged thyroid.
After asking you about various risk factors and symptoms, a proper examination for goiter is the probable next step.
If your doctor has a reason to suspect thyroid problems, blood tests can reveal a lot. The first sign of trouble is thyroid hormone levels above or below normal. Because the thyroid is controlled by another hormone, called thyroid-stimulating hormone (TSH), its level will be checked as well.
The doctor may want to get a better view of the thyroid. Ultrasound, and other imaging tests, can help reveal information about the size and condition of the thyroid that a simple physical exam cannot.
Because of the differences between Graves' and Hashimoto's diseases, some additional tests may help diagnose the former.
A radioactive iodine uptake test and a thyroid scan show the doctor how much iodine your thyroid is absorbing from your bloodstream and where it's storing it. This will help the doctor distinguish between Graves' and other causes of hyperthyroidism.
Even though they are both autoimmune diseases affecting the thyroid, the treatment of Graves' disease versus Hashimoto's is quite different. The focus is on controlling the resulting hyperthyroidism or hypothyroidism, which requires a different approach.
Although rare, it is possible for Hashimoto's to turn into Graves' and Grave's to turn into Hashimoto's, so continuous monitoring of your condition following treatment is essential.¹³
Your doctor will most likely put you on levothyroxine medication to reduce the effects of hypothyroidism caused by Hashimoto's disease.
This is identical to the hormones produced by the thyroid. Taking it serves as hormone replacement therapy to make up for what your thyroid cannot produce.
Regular blood tests will be part of the treatment plan to dial in the correct dosage and keep an eye on any changes in your hormone levels.
The overactive thyroid caused by Graves' disease can't be treated by simply replacing the lost hormones. Instead, steps must be taken to reduce the amount of hormones produced by the thyroid.
Radioactive iodine therapy
The thyroid works by taking iodine from the bloodstream. When you take radioactive iodine, your thyroid will absorb it and then shrink in size due to the radiation.¹⁴ The substance is taken by mouth.
Certain medications, such as propylthiouracil and methimazole, inhibit the production of hormones by the thyroid.¹⁵, ¹⁶
In some cases, your doctor may decide that it's best to perform a thyroidectomy to remove all or part of the thyroid gland. This will prevent the gland from producing too much hormone but may require you to take hormone replacement such as levothyroxine to compensate.
Medical researchers use clinical trials to learn more about effective ways to diagnose and treat diseases like Graves' and Hashimoto's. Participating in a clinical trial can help others in a similar situation to yourself and provide you with better insights or treatment options for your condition.
Both Graves' disease and Hashimoto's disease are autoimmune disorders that result when antibodies from your immune system begin to attack the thyroid. The differing antibodies have opposite effects on the gland, however.
While Hashimoto’s causes the thyroid to become underactive, Graves' makes it overactive. Both conditions are treatable and rarely life-threatening.
If you suspect your thyroid isn't functioning properly, make an appointment to see your doctor.
Hashimoto's disease | National Institute of Diabetes and Digestive and Kidney Diseases
Hashimoto thyroiditis (2022)
Graves disease | NCBI Bookshelf
Smoking and thyroid (2013)
Thyroid disease & pregnancy | National Institute of Diabetes and Digestive and Kidney Diseases
Graves’ disease: Complications | NCBI Bookshelf
Hyperthyroidism (Overactive thyroid) | National Institute of Diabetes and Digestive and Kidney Diseases
Radioactive Iodine | American Thyroid Association
Propylthiouracil (PTU) | NCBI Bookshelf
Methimazole | NCBI Bookshelf
Want all the latest clinical trial and HealthMatch news in your inbox? We thought you might! Sign up below.