Rheumatoid arthritis (RA) is a chronic autoimmune disorder that causes joint pain and inflammation. Research has shown interesting links between RA and other autoimmune conditions, one of which is hypothyroidism. An autoimmune disease is a condition in which your body’s immune system attacks healthy cells by mistake. Hypothyroidism, caused by an underactive thyroid gland, occurs when the thyroid gland doesn’t produce enough of its natural hormones.

When someone experiences multiple health conditions at once, such as RA and hypothyroidism, they’re called comorbidities. One myRAteam member said, “I have multiple autoimmune diseases: RA, and recently diagnosed with an underactive thyroid. Anyone else with multiple autoimmune diseases?”

Studies have shown that people with RA have an elevated risk of developing hypothyroidism, making it a common comorbidity.

In this article, we’ll explore the relationship between hypothyroidism and RA and the importance of managing these two conditions to improve your well-being.

Understanding Hypothyroidism

Hypothyroidism is a disorder of the thyroid, a butterfly-shaped gland located in the neck. It’s responsible for producing hormones that regulate the body’s processing of food and energy — also known as your metabolism. The thyroid hormones also control various bodily functions including heart rate and body temperature.

Symptoms of Hypothyroidism

In hypothyroidism, the thyroid gland does not release enough thyroid hormones. This deficiency can cause several symptoms, which can vary in severity and commonly include:

• Fatigue
• Weight gain
• Constipation
• Dry skin
• Hair loss
• Cold intolerance
• Muscle weakness
• Heavy menstrual periods
• Depression

Sometimes, hypothyroidism can cause muscle aches, joint pain and stiffness, swelling of the small joints in the hands and feet, and carpal tunnel syndrome. These symptoms are often nonspecific and can be mistaken for other health issues, including RA, making diagnosis difficult without a full medical evaluation.

Diagnosis of Hypothyroidism

Diagnosis may be done with a combination of medical history, physical exam, imaging, and blood tests. Blood tests may include the levels of thyroid-stimulating hormone (TSH), T3, and T4 in your body. Imaging tests may also look at how your thyroid gland looks and works.

Causes of Hypothyroidism

The most common cause of hypothyroidism is autoimmune thyroid disease, also known as Hashimoto’s thyroiditis. In Hashimoto’s thyroiditis, the body’s immune system attacks the thyroid gland, leading to inflammation and impaired hormone production.

Other causes of underactive thyroid disorders include iodine deficiency, certain medications, and thyroid surgery. According to MedlinePlus, people who are more likely to have hypothyroidism include:

• Women
• Those older than 60
• Those who have undergone radiation treatment to the neck and chest area
• Those who are or were recently pregnant
• Those with Sjögren’s syndrome, type 1 diabetes, rheumatoid arthritis, lupus, and other autoimmune conditions

Treatment for Hypothyroidism

Hypothyroidism is typically treated with synthetic (human-made) thyroid hormones as substitution therapy. One such drug, levothyroxine, helps to replace the hormones that the thyroid isn’t naturally producing. The goal of replacement therapy is to increase thyroid hormone levels to normal and maintain them.

The Connection Between Hypothyroidism and RA

Research suggests that people with RA may have a higher risk of developing hypothyroidism than the rest of the population, and vice versa. Scientists don’t fully understand the reasons for this connection, but they have some guesses.

Shared Risk Factors

One member shared, “I was diagnosed at 17 with hypothyroidism and 55 with RA. Wonder if they could have diagnosed the RA earlier?”

RA and hypothyroidism share some common risk factors. Both have a strong autoimmune component, implying that a disordered immune system plays an important role in their development.

Genetics also play a crucial role in the risk of developing both RA and hypothyroidism. Having a family history of either condition can increase an individual’s likelihood of developing the other.

Thyroid Hormones in the Joints

One theory about the relationship between RA and thyroid disease was published in Nature. Scientists hypothesized there’s a connection between thyroid hormones and the inflamed tissues in the joints of people with RA and osteoarthritis. Using several research methods, the researchers found that the thyroid hormones in the joint fluid of people with RA were more broken down. They further discovered a network of thyroid hormones in the inflamed joints of people living with RA. This study may shed more light on the relationship between thyroid disease and RA.

Medications and Their Role

Certain medications for RA can affect the thyroid gland and potentially lead to hypothyroidism as a side effect. For example, drugs like propylthiouracil — used to manage hyperthyroidism — may be associated with an increased risk of developing RA. Additionally, prolonged use of glucocorticoids, a common RA treatment, can interfere with the production and processing of thyroid hormones, leading to hypothyroidism.

One large study conducted in Sweden and published in the Journal of the American Medical Association found that people with RA have a higher rate of thyroxine-treated autoimmune thyroid disease at diagnosis. This means they were diagnosed with and treated for hypothyroidism before they were diagnosed with RA. This study revealed a need for additional research on the relationship between medications, hypothyroidism, and RA.

One member asked, “Are thyroid problems related to the RA or the medications? I’ve packed on about 35 pounds this year. I assumed it was from three years of prednisone, but even after tapering down and cutting back on junk food, I am still gaining rapidly.”

If you’re experiencing symptoms of hypothyroidism such as weight gain and fatigue, ask your doctor about whether it could be related to your RA medications.

Complications and Prognosis

Having both RA and hypothyroidism can affect the prognosis (outlook) and overall management of each condition. The presence of comorbidities can complicate treatment plans, making it more challenging for health care providers to manage the conditions effectively.

Additionally, some symptoms of hypothyroidism, such as fatigue and muscle weakness, can overlap with RA symptoms, leading to difficulties in diagnosing and monitoring both conditions accurately.

Importance of Managing Comorbidities

Managing comorbidities is necessary to maintain your health and quality of life while living with both RA and hypothyroidism. For managing hypothyroidism, your endocrinologist or rheumatologist will need to regularly monitor your thyroid hormone levels and disease activity. Effective management of one condition can also positively impact the other, leading to better overall health outcomes.

Fortunately, your rheumatologist can help treat both of your conditions. “I have hypothyroidism, rheumatoid arthritis, chronic fatigue syndrome, fibromyalgia, and Sjögren’s. I couldn’t make it without my rheumy,” a member wrote.

As another member explained, “There is no cure for RA or hypothyroidism, but when you have the right meds, it does slow the progression of your diseases.”

Equipping yourself with knowledge is the first step toward proper management of all of your medical conditions and a good quality of life.

Talk With Others Who Understand

On myRAteam, the social network for people with rheumatoid arthritis and their loved ones, more than 203,000 members come together to ask questions, give advice, and share their experiences with others who understand life with RA.

Are you living with both hypothyroidism and RA? What advice do you have for others living with two chronic conditions? Share your experience in the comments below or join the conversation on your Activities page.