Thyroid eye disease (TED) is an autoimmune disease. This means the body’s immune system can no longer tell the difference between healthy cells and harmful invaders like viruses, fungi, or bacteria.1,2
Because it cannot tell the difference, the immune system of a person with TED begins to attack healthy tissue, fat, and muscle behind and near the eyes. This causes inflammation, swelling, and pain in and around the eyes.1
Like many other autoimmune conditions, research shows that people who develop thyroid eye disease may have inherited genes that make them more likely to develop autoimmune conditions.1,3
Doctors also know that people with TED are at greater risk of having or developing other autoimmune conditions. This could be another sign that genes play a role in who develops TED.3
About 5 out of every 100 people have an autoimmune disorder. About 19 out of every 100,000 people have TED.3,4
TED can occur with other conditions as well. Coexisting conditions are known as comorbidities. The term comorbidity is used to describe a condition or illness that occurs at the same time of another condition or illness. Comorbid illnesses can interact in ways that worsen both. Morbidity should not be confused with the term mortality. Morbidity means disease or illness, while mortality means death.5
Autoimmune conditions
It is hard for doctors to know exactly how many autoimmune conditions can coexist with TED. The most common include:6-12
- Graves’ disease, a condition where the immune system attacks the thyroid gland, causing an excess of thyroid hormone. This leads to increased thyroid function (hyperthyroidism).
- Hashimoto’s thyroiditis, a condition where the immune system attacks the thyroid gland, causing decreased function (hypothyroidism).
- Rheumatoid arthritis, a type of arthritis that causes inflammation, joint pain, stiffness, and swelling.
- Psoriasis (sore-i-uh-sis), which causes inflammation inside the body that appears on the skin. The most common form is plaque psoriasis that causes raised red, dry, and silvery scale-like patches on the skin.
- Lupus, a disease where the immune system attacks healthy tissue, such as the skin, joints, kidneys, brain, and other organs.
- Vitiligo (vit-ih-lie-go), a condition that attacks the pigment cells in the skin, causing a loss of pigment in patches of skin all over the body.
- Type 1 diabetes, a condition where the body destroys insulin-producing cells in the pancreas. Insulin is needed to let glucose (sugar) into the body’s cells for energy. In type 1 diabetes, the pancreas cannot make insulin. This leads to a buildup of sugar in the blood, which can be life-threatening.
Other conditions that occur with TED
Research shows that other conditions may also occur with TED, including:13-16
- Type 2 diabetes, like type 1 diabetes, type 2 diabetes is a condition caused by high blood sugar. In those with type 2 diabetes, the body works hard to release enough insulin to keep blood sugar levels down. Over time, the body cannot make enough insulin to keep up. This leads to a buildup of sugar in the blood. People who have both type 2 diabetes and TED tend to have a more severe form of TED.
- Anxiety and depression, which are mental disorders that affect mood. People with TED often have cosmetic changes to their faces that can greatly impact their mental health. Your face is often your first impression. When you have a condition like TED, your mental health and self-confidence can suffer. One study showed more than 6 out of 10 people with TED said their appearance impacted their mental health.
Treating a secondary disease
Treatment will be different depending on the type of secondary condition the person with TED develops. For example, diabetes treatments are different from treatments for anxiety and depression. Talk to your doctor about the best treatment choice for you.