Rheumatoid Arthritis and Thyroid Eye Disease: What Is the Connection?

Over the years, doctors and researchers have focused more attention on comorbidities, which are 2 or more illnesses or conditions that happen at the same time in a person. Comorbid illnesses can interact in ways that make both worse.

New research has found a possible connection between rheumatoid arthritis (RA) and thyroid eye disease (TED), which are both autoimmune diseases.¹

Autoimmune disease

Autoimmune diseases and disorders occur when the body’s own immune system cannot tell the difference between healthy cells and harmful invaders like germs.^2,3

It is not completely clear what causes autoimmune diseases. However, it is most likely they are caused by both genes and the environment. People with autoimmune diseases tend to have more than 1 person in their family that has the disease. This means that genetics can be an important factor in who will get a disease.

Studies have shown that people who develop RA might also be more likely to develop other autoimmune conditions. This is because of genes passed on from families. This has led doctors to believe that genetics have a role in who gets TED.^1,3

About 5 out of every 100 people have an autoimmune disorder. About 19 in every 100,000 people have TED.^4,5

What is thyroid eye disease?

Thyroid eye disease (TED) is a rare autoimmune disease.²

Antibodies are proteins your body makes to kill germs. In TED, harmful antibodies attack various parts of the body, including the tissues around the eyes. This results in inflammation and damage to the muscles, connective tissues, and fat around the eyes. Damage and inflammation are progressive, with an active and inactive phase.²

Thyroid problems and joint symptoms

Low-functioning thyroid is known as hypothyroidism. Hypothyroidism can cause muscle and joint problems. Some of these problems include:⁷

• Joint stiffness, pain, and swelling
• Muscle pain and stiffness
• Carpal tunnel syndrome, which is narrowing and swelling of the wrist that causes nerve pain

The most common form of hypothyroidism is Hashimoto’s disease, an autoimmune disorder. While high functioning thyroid levels (hyperthyroidism) are more common in those with TED, Hashimoto’s or hypothyroidism can occur. This is 1 connection between thyroid problems, TED, and joint problems.⁸

Treatment for thyroid eye disease and rheumatoid arthritis

Autoimmune disorder treatments are aimed at decreasing pain and inflammation. Treatments usually:⁹

• Reduce symptoms – Pain killers, anti-inflammatories, and sometimes surgery can be used to decrease symptoms.
• Replace missing components in the body – Certain hormones in the body are out of balance in some disorders. For example, treatment for thyroid disorders might include replacing these hormones.
• “Turn down” the immune response – Some drugs used for autoimmune disorders turn down the body’s harmful over-reactive immune response. Each of these drugs is different and has its own risks and benefits.

Things to know about TED and RA

If you have joint problems and TED, it may or may not be RA. Many people have joint problems without having RA. However, early and effective treatment for RA is essential for the best outcomes and management of RA. For this reason, it is vital to report joint or muscle symptoms to your doctor when they occur.⁶

People with TED may or may not have thyroid problems. Thyroid problems, TED, and RA are separate disorders requiring different treatments. Talk to your doctor about any and all symptoms you have in order to get the right diagnosis and treatment.²