The Thyroid Mystery: Exploring the Link Between Hypothyroidism and Muscle Pain

Having a chronic condition like hypothyroidism can feel demoralizing. Experiencing muscle pain and hypothyroidism can be downright depressing, not to mention painful and debilitating. 

Did you know that your muscle pain could be caused by hypothyroidism, and not something in addition to it? This realization can change your whole outlook on the situation. 



Read on to discover how muscle pain can be caused by hypothyroidism and what you can do to address the problem by treating its source, as well as other helpful lifestyle options that can enhance your muscle function and overall sense of well-being.

Table of Contents

Yes. Among the many possible causes of muscle pain is hypothyroidism. 

Any disease affecting the muscles is referred to as myopathy. Hypothyroid myopathy is a muscle malady caused by hypothyroidism that occurs in about 80% of cases. It is usually the result of uncontrolled or untreated thyroid hormone deficiency.

There are four main subtypes of myopathy caused by hypothyroidism:



1. Myasthenic syndrome: A congenital disorder involving a defect in nerve cell signal transmission to muscles. It causes muscle weakness that is aggravated by exertion.
2. Atrophic form: Severe muscle atrophy
3. Kocher Debre Semelaigne syndrome: Usually seen in children, this condition can cause muscle hypertrophy, short stature, and cretinism.
4. Hoffmann syndrome: Usually seen in adults, this condition can cause hypertrophy, stiffness, spasms, and weakness of muscles, especially of the arms, legs, and tongue. 
   

Hypothyroidism is a condition in which the thyroid gland does not produce enough thyroid hormone to properly regulate metabolism, energy levels, and the function of the brain, bones, and muscles. There are multiple reasons why hypothyroidism and muscle pain often occur together.

Carnitine is a natural substance that helps turn fat into energy. It is made in the liver and kidneys and stored in the skeletal muscles, heart, and brain. A decrease in muscle carnitine has been found in patients who experience hypothyroid myopathy.

It seems that, in hypothyroidism, the body’s poor ability to regulate metabolism is operative even at the level of the muscles. Low levels of carnitine cause weakness of the muscles in the:

• Hips
• Shoulders
• Upper arms; and 
• Legs

The primary form is caused by a genetic defect and hinders the body’s ability to move carnitine into cells. 



However, several health conditions can cause secondary carnitine deficiency. This form, involves low levels of carnitine in the blood and can be treated with carnitine supplementation and avoidance of trigger behaviors, such as rigorous exercise, skipping meals, and exposure to cold.

The thyroid hormones help regulate glucose levels in the blood. In hypothyroidism this function is not performed and glucose levels do not remain balanced, sometimes leading to insulin resistance. 

Insulin resistance can result in diabetes if it persists long enough. Studies of the muscles of diabetic patients have shown various abnormalities that include:

• Increased glycolytic fiber numbers. These are the fibers that fatigue more quickly since they create energy (ATP) through anaerobic means and thus make less of it than slow oxidative fibers
• Muscle atrophy
• Muscle metabolism disturbances
• Muscle weakness
• Decreased muscle plasticity, meaning the muscle is less able to alter its structural and functional properties to accommodate demands placed on it 

Skeletal muscle cells lose their insulin responsiveness before other cells, which might explain how prevalent muscle pain is in patients with hypothyroidism. Changes in mitochondrial function have been proposed as contributing to the phenomenon.

Mitochondria are the powerhouses of the cell because they metabolize sugar to make energy. If metabolism is disrupted, it could be a result of changes in mitochondrial function. 



Another contributing factor to insulin resistance is oxidative stress, which is increased in patients with hypothyroidism.

It is unclear how hypothyroidism causes myopathy, but some experts believe that thyroxine (T4) deficiency is to blame for impaired muscle function. 



Thyroid hormones play a role in muscle contraction, metabolism, and cell regeneration, as well as controlling mitochondrial function. Aging is associated with lower thyroid hormone levels in the blood as well as a decrease in muscle mass, strength, and quality.

Evidence of hypothyroid myopathy can take many forms, including:

• Weakness, especially in large muscles like the thighs and shoulders
• Slower muscle reflexes and eventually a decrease in overall coordination due to deterioration of the myelin sheath surrounding nerve processes
• High creatinine levels, perhaps due to rhabdomyolysis, or the breakdown of muscle fibers
• Muscle cramping, aching, tenderness, or stiffness
• Myoedema (swelling in response to a pressure stimulus on the muscles of the arm)

In rare cases, muscles may be enlarged and weakened (as in Hoffmann’s syndrome) or atrophied (as in rhabdomyolysis, which can be life-threatening).



If you have hypothyroidism and are experiencing these symptoms, HealthierU can support you in managing and treating them. Call today for an initial consultation.

A doctor can confirm hypothyroid myopathy and determine what is causing it during a physical examination. 



You will explain your symptoms and receive diagnostic testing. You may have a blood test to measure creatine kinase, high levels of which indicate muscle damage. The levels can be as high as 10 to 100 times greater than the normal level, but they are not directly proportional to the degree of muscle damage. Depending on the findings, your doctor may recommend other tests as well.

Electromyography is a low-risk test in which electrodes inserted through the skin into the muscle record electrical activity in your muscle fibers. Although the results of this test are normal in about half of patients with hypothyroidism and muscle weakness, abnormalities in muscle function can present in the following ways:

• Motor unit potentials are polyphasic (consist of 4 or more phases rather than the typical 2 or 3 phases).
• Motor unit potentials have a lower amplitude than normal, meaning that fewer muscle fibers are responding to stimuli.
• Increased insertional activity indicates a loss of nerve supply to muscle tissue.

Electromyography is often performed in conjunction with a nerve conduction study to provide a more complete picture of the cause and severity of the irregularities. 



A nerve conduction study may show a gradually decreasing response to low-rate nerve stimulation and a gradually increasing response to high-rate nerve stimulation, indicating a neuromuscular junction abnormality.

A muscle biopsy involves removing a small sample of muscle tissue to be examined under a microscope. This is a minor surgical procedure that is recommended if you have severe symptoms and inconclusive or unclear diagnostic results after other testing. 

A biopsy may appear normal in individuals with hypothyroid myopathy, but in rare cases, it will show enlargement (hypertrophy) of slow-twitch muscle fibers, which occurs as muscles attempt to compensate for the atrophy of fast-twitch muscle fibers. This is called Hoffmann’s syndrome, which is a specific form of hypothyroid myopathy.

Other findings of this syndrome may include:



• Increased interstitial connective tissue
• Abnormal glycogen accumulation
• Increased numbers of nuclei in muscle cells
  

Nonsteroidal anti-inflammatory drugs, or NSAIDs, are commonly used to treat muscle and joint pain. However, if you need something to deal with pain and discomfort for the long term, it might be wise to consider something else. NSAIDs can have serious side effects, particularly if taken regularly.

Even in acute pain situations, such as an injury, taking NSAIDs can be counterproductive. They may reduce pain, but they can also interfere with the recovery of the muscle that has been injured. In the case of hypothyroid myopathy, where muscle is continually being broken down, NSAIDs may wind up inhibiting the removal of injured cells and thus not triggering the rebuilding of healthy cells.

Most studies have shown an improvement in muscle maladies after treatment with the hormone medication levothyroxine. When normal thyroid hormone levels are restored, patients generally experience complete alleviation of myopathic symptoms. Recovery, however, can be very slow, taking up to several months. 



Though hypothyroid myopathy seems to be reversible, it is best to begin treatment as soon as possible, since severe damage will take longer to correct.

The muscle breakdown correlated with hypothyroidism can cause chronic inflammation, which can bring about a whole host of health issues if not addressed. In addition, there are other specific ways hypothyroidism can cause inflammation. All these considered, an anti-inflammatory diet may counteract the chain of events set in motion by hypothyroidism. 

Anti-inflammatory diets have been found to reduce pain in patients who suffer from fibromyalgia (which is close in presentation to muscle pain with hypothyroidism), as well as rheumatoid arthritis and osteoarthritis.

Foods that are considered inflammatory include sugary, high-fat, and processed foods. Avoid these as well as excess alcohol, dairy, red meat, and soda.

Eating a nutrient-dense diet low in carbohydrates may help reduce inflammation. Consider adding several of the following foods to your diet:

• Fruits: Rich in carotenoids, flavonoids, and antioxidants, all of which play a role in reducing inflammation
• Green, leafy vegetables: Rich in magnesium, deficiency of which is linked to systemic inflammation
• Whole grain, nuts, seeds, and beans: Rich in magnesium
• Healthy fats such as olive oil, avocados, and fish: Contain omega-3 fatty acids
• Kefir, Greek yogurt, and fermented vegetables: Rich in prebiotics and probiotics
  

Although it may seem counterintuitive, working the affected muscles can help them stay healthier and minimize the damage they sustain from myopathy. 

Gentle, low-impact aerobic exercises such as swimming, walking, and stationary cycling can help maintain muscular efficiency as well as combat depression, fatigue, and weight gain.



You may need physical therapy or occupational therapy to relearn how to perform activities of daily living with muscle weakness.

If you are experiencing muscle pain with hypothyroidism, reach out to HealthierU for personalized support. 



You will receive assistance with developing a plan for dietary and other lifestyle changes that can help you manage or even eliminate the symptoms of hypothyroidism that affect your muscles.

Contact us today to schedule a free nutrition consultation and begin taking steps to restore and relieve your muscles that have been adversely affected by hypothyroidism.