Neuropathy involves damage to the nerves. In some cases, people with hyperthyroidism may develop neuropathy.

This article explores the link between hyperthyroidism and neuropathy, other common causes of neuropathy, and additional neurological symptoms of hyperthyroidism.

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Hyperthyroidism involves an excess, or overproduction of, thyroid hormones. This can lead to symptoms such as:

According to 2019 research, the prevalence of neuromuscular disorders such as neuropathy in people with thyroid disorders ranges from 20–60%. The research also indicated that people with hypothyroidism were more likely to develop neuropathy than those with hyperthyroidism.

People with hyperthyroidism were also at an increased risk of developing proximal myopathy (symmetrical muscle weakness in certain limbs). This condition differs from neuropathy in that it primarily affects the muscles instead of the nerves. Both myopathy and neuropathy lead to muscle weakness.

Although hyperthyroidism can lead to neuropathy, according to 2017 research, neuropathy in hyperthyroidism is not common. However, it can still occur. Neuropathy associated with hyperthyroidism may occur for a number of reasons.

Hyperthyroidism may cause a person’s body to go into a hypermetabolic state, when the amount of energy the body uses while at rest increases. This depletes the nerves of important nutrients and may lead to nerve damage and symptoms of neuropathy.

In some cases, a person may have excess thyroid hormones in the peripheral tissues of their body. Peripheral neuropathy may occur as a direct result of those excess hormones.

Certain autoimmune diseases may also lead to hyperthyroidism. For example, Graves’ disease may affect thyroid hormone production and cause hyperthyroidism symptoms. Graves’ disease may also cause neuropathies.

Neuropathy is not the only neurological symptom that can develop due to hyperthyroidism. Thyroid hormones play an important role in different aspects of the nervous system. When hormone levels become too low or too high, it may cause neurological issues.

Mood and cognitive disorders

According to older research, the close relationship between thyroid function and nervous system function may lead to neurological symptoms, such as disorders that affect a person’s mood and thought-processing capability.

Tremors

Tremors of the face, hands, and legs may also occur in people with hyperthyroidism.

Researchers believe that tremors occur due to excess thyroid hormone stimulating the beta-adrenergic system. About 58.2% of children with thyrotoxicosis due to hyperthyroidism developed tremors. (Thyrotoxicosis is when a person has too much thyroid hormone in their body.)

Encephalopathy

Encephalopathy involves impaired brain function. Research indicates it can occur due to hyperthyroidism from autoimmune thyroid disease. The majority of people with encephalopathy due to autoimmune thyroid disease have Hashimoto’s thyroiditis, and a small number have Graves’ disease.

Hashimoto’s thyroiditis is the cause of hypothyroidism in the vast majority of cases. Encephalopathy due to hyperthyroidism is much less common.

Many other conditions can lead to symptoms of neuropathy.

Hypothyroidism

Although excess thyroid hormones can cause neuropathy, more frequently, hypothyroidism causes peripheral neuropathy. The authors of a 2016 study suggested that neuropathy develops in people with hypothyroidism in the early stages of the disease.

Injury

According to the National Institute of Neurological Disorders and Stroke, physical injury is the most common cause of single nerve injury leading to neuropathy. Injuries from falls, sports, and car accidents can compress, crush, or stretch nerves, which can lead to neuropathy.

Surgery side effects

Different types of surgery can temporarily or permanently cause nerve damage. For example, the incidence of nerve palsy (paralysis or weakness), which can lead to neuropathy, after hip replacement ranges from 0.17% to 4%.

Hip surgery also carries a risk of damage to the sciatic nerve or femoral nerve, which can lead to neuropathy.

Diabetes

Diabetes is also a leading cause of neuropathy in the United States. The condition can cause damage to the motor, sensory, and autonomic nerves, causing symptoms of neuropathy. Approximately 60–70% of people with diabetes have some level of nerve damage.

Vitamin deficiency

Vitamin deficiencies may also affect the nerves in the body. For instance, a deficiency in vitamin B12 can cause symptoms of neuropathy.

Alcohol use disorder

Alcohol can damage the nerves in the body. Over time, this damage can lead to alcohol-related neuropathy. Researchers estimate that of people with alcohol use disorder in the U.S., 65% also have related neuropathy.

Infection

Various types of infection can attack a person’s nerves and lead to neuropathy. Some viruses, including herpes simplex, West Nile virus, and varicella-zoster virus, may affect sensory nerve fibers.

Additionally, a 2022 study suggests that 56.3% of people who have had COVID-19 may develop peripheral neuropathy and myopathy.

Chemotherapy side effects

Various forms of chemotherapy to treat cancer can affect the nerves and cause neuropathy. The risk of neuropathy depends on the specific drugs administered.

About 30–40% of people who receive chemotherapy develop some level of neuropathy. The length of time it takes for neuropathy symptoms to resolve after stopping chemotherapy treatment may vary.

People with hyperthyroidism should carefully monitor their condition with the help of a healthcare professional. Thyroid hormones play a crucial role in many body functions. A disturbance in thyroid hormone levels can cause an array of symptoms.

If a person experiences symptoms of neuropathy, they should contact a doctor. Symptoms may include:

  • muscle weakness
  • muscle numbness or loss of feeling
  • muscle tingling
  • difficulty with movement

Hyperthyroidism may cause neuropathy due to a number of factors, although researchers do not yet fully understand the link between the conditions.

Other more common causes of neuropathy include injury, diabetes, and hypothyroidism.

A person should talk with a doctor if they think they may have hyperthyroidism or neuropathy. A doctor can provide an accurate diagnosis and appropriate treatment.