The Connection Between Hypothyroidism and Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an autoimmune disease where the body’s immune system attacks its own healthy tissues. This response is called autoimmunity, and it causes severe inflammation (painful swelling) that attacks the linings of joints. RA can also affect the organs, including the skin, eyes, and heart. 

Research shows people with RA are more likely to develop underactive thyroid disease, including hypothyroidism and Hashimoto’s thyroiditis. And that connection appears to go both ways in that people with thyroid disease have a higher risk for RA. Here is what you need to know about underactive thyroid conditions and how they are connected to RA. 

Your Thyroid 

Your thyroid is the tiny butterfly-shaped gland in your neck and is made up of two lobes located on both sides of the trachea (windpipe). A normal thyroid is not outwardly visible and cannot be felt when pressure is applied to the neck.

The thyroid gland produces and stores hormones to regulate metabolism (the rate that cells perform their jobs). Thyroid hormone is also vital to the growth and development of the human body.

Thyroid hormone regulates many of the body’s functions by consistently releasing a fixed amount of thyroid hormone into the bloodstream. There are instances where the body will need more energy—such as during pregnancy—so the thyroid gland will produce more hormones.

Hypothyroidism 

Hypothyroidism occurs when the thyroid gland is underactive and is not making enough thyroid to keep the body functioning properly. A diagnosis of hypothyroidism can be made when there is too little thyroid hormone in the blood.

Signs of hypothyroidism will develop slowly and over several years. Symptoms may include:

• Fatigue
• Increased sensitivity or intolerance to the cold
• Weight gain
• Dry hair and skin
• A pale, puffy face
• Muscle aches
• Depression
• A goiter (an enlarged thyroid gland)
• A hoarse voice

See your doctor if you have been feeling tired for no reason or have other signs of hypothyroidism, including a puffy face or a hoarse voice. 

Hashimoto’s Thyroiditis

Much like RA, Hashimoto’s thyroiditis is an autoimmune disease. This condition causes the immune system to mistakenly attack the thyroid gland.

Over time, these attacks will destroy thyroid tissue and reduce thyroid production, leading to an underactive thyroid. Hashimoto’s thyroiditis can be difficult to diagnose, and in many instances, a person with the condition may go many years undiagnosed.

One of the first signs of Hashimoto’s thyroiditis is an enlarged thyroid, causing the front of the neck to appear visibly swollen.  

Additional symptoms of Hashimoto’s thyroiditis include:

• Severe fatigue
• Weight gain
• A puffy face
• Muscle and/or joint pain
• Hair loss
• A slow heart rate
• Irregular and heavy menstrual periods

Tell your healthcare provider as soon as you start to experience symptoms of Hashimoto’s thyroiditis, including feeling chronically tired, dry skin, and a pale, puffy face. This is especially important if you have a family history of Hashimoto's thyroiditis or other autoimmune diseases.

RA—Hypothyroidism Connection

Rheumatoid arthritis and underactive thyroid disease often coexist. A study published in 2018 showed an increased prevalence of autoimmune thyroid disease among people with RA during the first five years before diagnosis. This study also found the risk increased around the time of diagnosis and decreased two to five years after diagnosis. 

An observational study from 2017 in the journal Medicine found the prevalence of thyroid disorders in people with RA to be around 15.7%. Hypothyroidism was the most frequent disorder affecting up to 30.4% of the study participants with RA.

This observational study also found thyroid disorders in people with RA might indicate a more aggressive disease and poor treatment outcomes. The study’s authors note the importance of diagnosing coexisting thyroid disorders earlier by checking thyroid hormone levels in RA patients at the time of diagnosis and every year after.

Research also shows people who have autoimmune thyroid disease are at a higher risk for developing RA. One older study from 2010 reported in the American Journal of Medicine found people with autoimmune thyroid diseases like Hashimoto’s thyroiditis have a higher risk for RA.

Here, researchers found that 14% of study participants with Hashimoto’s thyroiditis also had another autoimmune disease.

Hypothyroid Joint and Muscle Symptoms

For some people, hypothyroidism can cause joint and muscle pain, and for people with RA, this might mean increased symptoms.

Musculoskeletal symptoms of hypothyroidism may include:

• Muscle aches, tenderness, and stiffness
• Muscle weakness
• Joint pain and stiffness
• Swelling of the small joints of the hands and feet
• Tingling, prickling, burning, or numb feeling in the hands or feet—a symptom called acroparesthesia

Because people with hypothyroidism have an increased risk for RA, any pain, stiffness, and swelling you may experience that doesn’t improve with thyroid treatment should be brought to the attention of your doctor. They can look for other possible causes of your muscle and joint pain.

You should also let your doctor know if RA pain and symptoms worsen after a thyroid disease diagnosis. They can see which condition is causing symptoms and adjust your treatment plan.

Treatment for Hypothyroidism With RA

Treatment for hypothyroidism is the same whether or not a person has rheumatoid arthritis. It generally involves life-long treatment of synthetic thyroid hormone replacement, which is available as a daily pill.

It is also important for people living with hypothyroidism to have routine follow-ups with an endocrinologist to check thyroid hormone levels to make sure they remain in the normal range. Depending on where hormone levels are, medication dosages may need to be adjusted.

It is also important to manage RA and keep it under control. Your doctor is in the best position to answer questions about your treatment plan and how to best manage a thyroid condition while living with RA.

A Word From Verywell

Most thyroid disorders can be well-managed with medication and are not life-threatening. But it is important that you take your medication every day. In addition, your healthcare provider will monitor your hormone levels and treatments and adjust medications over time.

It might take some time to find the right treatment and get hormone levels back to normal, but most people with thyroid disorders can have normal lives without any restrictions.