Understanding Muscle Pain and Weakness in Thyroid Disease

Muscle disease, or myopathy, may occur because you have an underactive thyroid (hypothyroidism) or an overactive thyroid (hyperthyroidism). As a rule, muscle problems related to these medical conditions are usually mild. You can ease your symptoms through prompt treatment of the thyroid disorder.

However, in some rare cases, myopathy related to thyroid disease can be severe and debilitating.

By gaining a better understanding of the muscle symptoms of thyroid disease, you'll be able to treat any discomfort or weakness.

This article will talk about thyroid disease and how it can cause pain and weakness. It will discuss thyroid disease symptoms and how a healthcare provider diagnoses and treats the disease.

Myopathy in Thyroid Disorders

Verywell / Laura Porter

Myopathy in Hypothyroidism
  • Weakness in muscles close to the center of the body (thighs, shoulders)

  • Cramping

  • Elevated creatinine

  • Rarely, enlarged muscles (Hoffman's syndrome)

  • Rarely, breakdown of muscle tissue (rhabdomyolysis)

Myopathy in Hyperthyroidism
  • Muscle weakness

  • Creatinine levels tend to be normal

  • Cramping (uncommon)

  • Rarely, issues with the muscles involved in swallowing and breathing (rare)

Hypothyroid Myopathy

Muscle weakness, aches, and cramping are common in people with hypothyroidism.

Symptoms

People with hypothyroid myopathy experience weakness throughout the body. They typically experience it in the muscles of the thighs or shoulders. This can lead to problems climbing stairs or even combing your hair.

High Creatinine Kinase Levels

In addition to muscle symptoms, you may have a high creatinine kinase level when your healthcare provider gives you a blood test. Creatinine kinase is a muscle enzyme that is released into the blood when there is a muscle injury. But your creatinine kinase level is not necessarily linked to the severity of your muscle pain.

Rarely, hypothyroidism can cause more severe muscle symptoms. One example is Hoffman's syndrome. This is when a person develops muscle hypertrophy (enlarged muscles). It can lead to significant muscle stiffness, weakness, and pain.

Rhabdomyolysis, a condition where muscle breaks down rapidly, is another rare muscular sign of hypothyroidism. It's often triggered by the combination of being hypothyroid and doing strenuous exercise. It may also occur when people take a statin, which is a cholesterol-lowering medication.

Recap

People with hypothyroid myopathy can experience weakness throughout the body. But they most often experience weakness in the center of the body, specifically the shoulders and thighs.

Sometimes hypothyroidism can cause more severe muscle issues. Hoffman's syndrome leads to muscle stiffness, weakness, and pain. Rhabdomyolysis causes muscles to rapidly break down.

Causes

While healthcare providers don't really know what exactly causes hypothyroidism-induced myopathy, some experts believe that the thyroxine (T4) deficiency seen in hypothyroidism leads to muscle injury and impaired muscle function.

Diagnosis

If you might have hypothyroid myopathy, your healthcare provider will ask about your symptoms and do a physical examination. They will order a blood test to measure creatinine kinase.

Your healthcare provider may recommend other tests, such as an electromyography. This is a test that uses needles to measure the electrical signals in your muscles and nerve cells while they're active and at rest.

Sometimes the healthcare provider may recommend a muscle biopsy to rule out other conditions. The healthcare provider will usually order a biopsy if your symptoms are severe.

Treatment

Treatment with the thyroid hormone replacement medication Synthroid (levothyroxine) can usually improve muscle symptoms like cramps and stiffness, although this improvement may take weeks. It usually takes several months for muscle weakness to go away.

Hyperthyroid Myopathy

Hyperthyroidism can also cause muscle weakness and sometimes cramping, but the symptoms tend to differ from myopathy related to hypothyroidism.

Symptoms

Muscle weakness in the shoulders and hips is the main symptom in people with hyperthyroidism. While muscle cramps and aches may occur, they are not as common as they are in myopathy related to hypothyroidism.

If someone has muscle weakness because of hyperthyroid myopathy, they may have difficulty climbing stairs, rising from a chair, and holding or gripping objects. They may also have trouble reaching their arms above their head.

People with hyperthyroid myopathy may experience weakness in the throat, face, and respiratory muscles. Rarely, in myopathy from hyperthyroidism, the muscles affected can include those that help you swallow and breathe.

The creatinine kinase level in the bloodstream is generally normal, despite the fact that your muscles are weak. Like in hypothyroidism-induced myopathy, the creatinine kinase level isn't related to the severity of a person's muscle symptoms.

Causes

Healthcare providers don't completely understand why myopathy occurs with hyperthyroidism. It's probably caused by the elevated level of thyroid hormones in the body. These high thyroid hormone levels may lead to increased breakdown of muscle protein as well as greater muscle energy use.

Diagnosis

As with myopathy in hypothyroidism, your healthcare provider will perform a physical examination and ask you questions about your muscle symptoms. They may also order blood tests, especially a thyroid function panel. Your healthcare provider may recommend an electromyography too.

Thyroid Disease Doctor Discussion Guide

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Treatment

Treatment of your hyperthyroidism will generally cure the myopathy. However, it can take time to improve—possibly up to several months—even after the thyroid is functioning normally again.

Summary

When you have thyroid disease, you might deal with muscle weakness and pain. Hypothyroid myopathy tends to cause muscle weakness in the center of the body, typically the shoulders and thighs. Hyperthyroid myopathy causes muscle weakness that rarely can affect swallowing and breathing.

Both types of myopathy improve with treatment of the underlying thyroid disease, but it can take time for symptoms to get better.

A Word From Verywell

Muscle complaints are common in thyroid disease. They can usually be soothed when your thyroid starts to function normally again. Coping strategies for easing muscle pain, regardless of the cause, may be useful in the meantime. Things like a massage, warm baths, and gentle exercise are good ways to help with the pain. Taking magnesium supplements can also soothe muscle cramps.

Still, it's important to see your healthcare provider if you notice new or significant muscle pain or weakness. While your thyroid may be the cause of your pain and weakness, there are other health conditions that can cause muscle symptoms as well. 

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7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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