Muscle Weakness and Thyroid Relationship

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The Thyroid, a gland that is located just in front of the windpipe in the neck, plays a role in cellular metabolism. The gland is responsible for secreting two primary hormones, including Thyroxine and Triiodothyronine1.

These hormones have a large number of functions to play in the body and have an impact on every single cell. The body’s general metabolism is regulated with the help of these two hormones, as well as many other functions that are required for various systems in the body to function at an appropriate level.

Symptoms associated with Thyroid disorders depend from patient to patient, as well as on the specific disease diagnosed. While weight-related changes are often considered primary symptoms of conditions affecting the Thyroid gland, some patients may experience weakness in their muscles, along with joint and muscle pain.

While the exact relation between these symptoms and Thyroid dysfunction has not been established by scientists, some breakthroughs have been made to shed light on the topic. In this post, we examine the potential connection between Thyroid-related disorders, muscle weakness, joint pain, and related symptoms.

Thyroid Diseases Explained

Certain conditions may cause the Thyroid to dysfunction, leading to either an increase in the presence of thyroid hormones within the body or a decline in these hormones. The primary conditions that a person can develop when it comes to their Thyroid gland include Hyperthyroidism and Hypothyroidism.

Hypothyroidism refers to a reduction in the Thyroid’s ability to secrete enough hormones to support cellular metabolic functions. Hyperthyroidism, on the other hand, is when there are too much of these hormones circulating through the body, often caused by the Thyroid gland becoming overactive and producing too many hormones.

Hypothyroidism is more common than Hyperthyroidism. According to one study, approximately 10% of the global population may be affected by this particular condition2. Female patients are also more suspectable to developing an underactive Thyroid, compared to male patients. Furthermore, the prevalence of Hypothyroidism also seems to greatly increase with age.

Hyperthyroidism is less commonly diagnosed. The prevalence of this particular condition may be up to 2%. Female patients are considered to be around at ten times higher risk of developing Hyperthyroidism when compared to the risk of this condition among male patients3.

Hypothyroidism and Muscle Weakness

When a patient develops hypothyroidism, it means the number of Thyroid hormones in their body has become too low. This causes metabolism to slow down, which is why a common symptom that the patient may experience when they have developed the condition would be weight gain – even when they have not changed anything in their diet.

Other common symptoms that the patient may experience when they have Hypothyroidism may include4:

  • Fatigue
  • Dry skin
  • An increase in the patient’s sensitivity toward cold weather
  • A slower heart rate
  • Hair may become thin
  • Memory function may be impaired
  • Signs of depression may be experienced
  • Hoarseness
  • The patient’s face may appear puffy

Due to the slowing of the metabolism, the patient is also likely to experience some digestive issues, with constipation being relatively common.

Apart from these issues, some patients who have Hypothyroidism tend to complain about the pain of their joints, as well as muscle weakness.

One study5 looked at the potential connection that may exist between Hypothyroidism and musculoskeletal problems. The study found a positive connection between the two – with a high prevalence of musculoskeletal pain and weakness reported by patients who had been previously diagnosed with this condition.

The pain was commonly experienced in the wrists, arms, lower limbs neck, back, and the ankles. Some patients also experienced generalized pain in their joints, as well as their muscles. Stiffness and cramping were also symptoms that were reported by some of the patients who took part in this particular study.

The Association Between Hypothyroidism And Musculoskeletal Symptoms

While not every patient will experience muscle weakness, along with joint-related symptoms, there are some who do tend to develop these symptoms when they have Hypothyroidism. At the moment, it is important to understand that scientists are not yet completely sure why the patient may experience such symptoms when their Thyroid hormone levels start to decline, but there are some theories that have been suggested.

Patients who have Hypothyroidism often also have an elevation in the level of Creatinine Kinase within their blood system. This is an enzyme that primarily interacts with muscles. In particular, Creatinine Kinase secretion is elevated when a muscle injury occurs.

This has led to the theory that the decline in levels of Thyroxine within the patient’s body may contribute to an abnormality with the body’s oxidative metabolism. What this means is that muscle tissue may be degraded and become damaged in the process. With this in mind, it would provide a reason for the elevated levels of the Creatinine Kinase enzyme that is often found in patients diagnosed with Hypothyroidism.

When this process leads to injury to the patient’s muscles, it causes an impairment in the functionality of their muscles. This would then ultimately contribute to the weakness that the patient would experience, along with the stiffness, cramps, and related stiffness.

A similar process may be to blame when it comes to looking at how Hypothyroidism could affect joints in the patient’s body. When oxidative stress is elevated, damage may not only be dealt to muscle tissue, but also to joints within the human body.

When joints and the surrounding tissues become damaged, it would lead to stiffness and pain in the joints. Additional symptoms that may occur would include inflammation, further leading to the symptoms that the patient may be experiencing.

Patients who present these symptoms along with Hypothyroidism will usually need to undergo certain tests in order to provide the physician with a thorough overview of the possible reasons behind their symptoms. Other causes that may be leading to muscle weakness and other related symptoms will also need to be considered.

The physician will usually start with a thorough physical examination and ask the patient to explain their symptoms. The patient’s Creatinine Kinase levels will usually be measured with a blood test. There are other types of tests that the physician may also have the patient undergo, such as a biopsy of their muscle tissue as well as another test known as an electromyography test.

Hyperthyroidism and Muscle Weakness

As previously mentioned, the development of Hyperthyroidism causes an elevation in Thyroid hormones within the patient’s body. This often leads to a reduction in weight, instead of weight gain, as metabolic processes are sped up due to the increase in Thyroid hormones that occur with the condition.

In addition to the reduction in weight, a patient who is diagnosed with Hyperthyroidism may also experience the following symptoms:

  • Tremors
  • An increase in bowel movements
  • Heart palpitations
  • Fatigue
  • Increased sweating
  • Nervousness
  • Anxiety

Muscle weakness is another possible symptom that may develop when a patient has an overactive Thyroid. In both Hypothyroidism and Hyperthyroidism, the reason behind the musculoskeletal symptoms that often develop is not completely understood. As with an underactive Thyroid gland, researchers and scientists do have some theories in terms of why muscle weakness and accompanying symptoms may occur in patients with Hyperthyroidism.

It has been found that in patients with an excess level of Thyroid hormones in their body, there is often an elevation in the speed at which muscle proteins are degraded. Energy usage by muscle tissue is also greatly enhanced. These two factors are thought to have a significant impact on the development of musculoskeletal symptoms, such as weakness and cramps, that the patient may experience.

The diagnosis process is quite similar to how patients will be examined when they have Hypothyroidism. A patient presenting musculoskeletal symptoms with Hyperthyroidism will obtain a physical examination from a physician. They will also be asked to provide a detailed explanation of the symptoms that they are experiencing. The doctor will have to rule out other potential causes for these symptoms by ordering certain blood tests. A Thyroid function panel test may also be ordered, along with electromyography.

All of these tests will help the physician get a better overview of how overactive the patient’s Thyroid gland is, as well as determine if there are any other underlying issues that may be contributing to muscle weakness, cramps, and pain.

Treating Musculoskeletal Symptoms In Thyroid Diseases

In the majority of cases where a patient is experiencing musculoskeletal symptoms in the presence of either Hyperthyroidism or Hypothyroidism, treatment will focus on restoring the balance of Thyroid hormones in the patient’s body. This can greatly help to relieve the symptoms that the patient is experiencing. In fact, some patients who develop a condition like a myopathy when they have a Thyroid disorder may find that their symptoms completely disappear when they undergo treatment for their Thyroid disorder.

The specific treatments that are available for the patient depending on the specific condition that the patient has. A number of tests may need to be performed for the physician to better understand the patient’s current Thyroid function. The physician will often not be able to provide an accurate treatment protocol when they only know that the patient has an underactive or overactive Thyroid. A root cause often also need to be identified – for example, in patients with Hypothyroidism, the most common cause is an autoimmune disease known as Hashimoto’s disease.

When a patient has Hypothyroidism, they may be provided a prescription for levothyroxine. This is a synthetic type of Thyroid hormone that helps to increase the level of Thyroxine in the patient’s body. The body can then convert the Thyroxine to Triiodothyronine, which is the most active form of Thyroid hormone. The most popular levothyroxine drug on the market at the moment would be Synthroid, but there are various brand names.

The idea of levothyroxine is to help elevate levels of Thyroid hormones, even when the Thyroid gland is unable to produce enough of these hormones.

In patients with Hyperthyroidism, medication will usually be provided to the patient to help slow down the function of their Thyroid gland. This will help to reduce the number of Thyroid hormones that are secreted by the gland, bringing their hormones into better balance.

In both cases, when Thyroid hormones become better balanced, the body’s metabolic processes will start to function normally again. The patient may find that symptoms like muscle weakness and joint pain improves, along with other problems, such as fatigue, weight issues, and more.


Various function in the body depends on the secretion of Thyroxine, as well as Triiodothyronine, from the Thyroid gland. Conditions that affect the secretion of these hormones, including Hypothyroidism and Hyperthyroidism, can have a significant impact throughout the entire body.

In some patients, the conditions may also contribute to issues such as joint pain, as well as pain and weakness in muscles.


1 M. Armstrong, A. Fingeret. Physiology, Thyroid Function. StatPearls. 6 Feb 2019.

2 A.G. Unnikrishnan, S. Kalra, R.K. Sahay, G. Bantwal, M. John, N. Tewari. Prevalence of hypothyroidism in adults: an epidemiological study in eight cities of India. Indian Journal of Endocrinology and Metabolism. 2013.

3 M.P.J. Vanderpump. The epidemiology of thyroid disease. Oxford Academic: British Medical Bulletin. 1 Sep 2011.

4 Hypothyroidism (underactive thyroid). Mayo Clinic.

5 D.N. Golding. Hypothyroidism presenting with musculoskeletal symptoms. Princess Alexandra Hospital and Harlow Group.


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