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Researchers have found that multiple sclerosis (MS) and thyroid disease frequently occur together. The thyroid is a small gland located toward the front of your neck, right under the Adam’s apple. Thyroid disease may be a potential complication of MS. It may develop as a result of MS itself or as a result of MS treatment.

For instance, treatment with Lemtrada (alemtuzumab) has been shown to induce thyroid disease in some people with MS. Another study found that males with MS are more likely to experience a co-occurring (or comorbid) autoimmune-related thyroid disease than females with MS.

As one MyMSTeam member shared, “My MS led to me having a thyroid problem. My doctor is watching it.” The relationship between thyroid disease and MS is complicated, and scientists are continuing to explore the connection.

What Are Autoimmune-Related Thyroid Diseases?

The thyroid plays a critical role in controlling metabolism; that is, the way the body turns food into energy. It does this by releasing and controlling specific hormones. Thyroid disease can lead to the gland producing too much or not enough hormones.

Like MS, thyroid diseases can have an autoimmune component. Autoimmune disorders are conditions in which the immune system attacks its own body and healthy cells.

One autoimmune-related thyroid disease connected to MS is Hashimoto’s disease. This condition causes hypothyroidism (an underactive thyroid, or too little thyroid hormone). Graves’ disease, another autoimmune-related disease, causes hyperthyroidism (an overactive thyroid, or too much thyroid hormone).

Hashimoto’s Disease

Hashimoto’s disease progresses over years. The inflammation associated with Hashimoto’s disease causes the body to not make enough thyroid hormone. The signs and symptoms of an underactive thyroid may include:

• Fatigue or sluggishness
• Muscle aches, tenderness, stiffness, or weakness
• Joint pain or stiffness
• More sensitivity to cold
• Constipation
• Pale, dry skin
• Puffy face
• Brittle nails
• Hair loss
• Swelling of the tongue
• Weight gain
• Prolonged menstrual bleeding
• Depression
• Trouble concentrating
• Memory lapses

Graves’ Disease

Graves’ disease is a common cause of hyperthyroidism that has also been associated with MS. Signs and symptoms of an overactive thyroid include:

• Anxiety or irritability
• Tremor of the hands or fingers
• Fatigue
• Heat sensitivity
• Heart palpitations
• Warm, moist skin and increased sweating
• Weight loss
• Bulging eyes
• Irregular menstrual cycles
• Reduced libido and erectile dysfunction
• Frequent bowel movements
• Thick, darkened skin on the tops of the feet or shins
• Sleep problems

What’s the Connection?

Researchers believe there may be two ways that thyroid disease and MS are associated.

Shared Risk Factors

Research suggests that MS has many risk factors; some are environmental and others appear to be genetic. Factors that increase inflammation, such as smoking and obesity, are thought to trigger underlying genetic processes that may ultimately lead to MS.

Thyroid diseases also have several risk factors. Both hypothyroidism and Graves’ disease have been linked to rheumatoid arthritis (a disease of inflammation), type 1 diabetes, and familial risk factors. This suggests that genetic factors also play a role.

Some risk factors are shared by MS and autoimmune-related thyroid diseases. For instance, research shows that certain genetic pathways and regulatory T-cell percentages (amounts of a type of white blood cell) are dysregulated in both MS and Hashimoto’s disease.

Overall, shared genetic factors may influence how the endocrine system and central nervous system work. These changes may affect thyroid function — and possibly the development of MS. Further studies are needed to understand how MS and thyroid conditions may overlap.

Thyroid Disease and Drug Treatments for Multiple Sclerosis

Drug treatments for MS may also potentially explain the association between MS and thyroid disease.

Treatment with alemtuzumab in people with MS has been shown to increase the risk of developing thyroid disease. In fact, thyroid autoimmune dysfunction (notably Graves’ disease) can occur in approximately 17 percent to 34 percent of people who take alemtuzumab for MS. Interestingly, one study found that people with MS who developed autoimmune thyroid disease after being treated with alemtuzumab actually responded better to the drug than people who didn’t develop autoimmune thyroid disease.

Another study found that treatment with interferon beta therapy also increased the risk of developing a thyroid condition.

Ultimately, the relationship between MS drug treatment and thyroid disease is complicated. Further studies are needed to clarify the connection.

Find Your Team

MyMSTeam is the social network for people with multiple sclerosis and their loved ones. More than 182,300 members come together to ask questions, give advice, and share their stories with others who understand life with multiple sclerosis.

Are you living with multiple sclerosis and thyroid disease? Share your experience in the comments below, or start a conversation by posting on MyMSTeam.