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Can Thyroid Problems Cause Low Testosterone?

Sep 10, 2021
Can Thyroid Problems Cause Low Testosterone?

Thyroid disease in men can cause low sperm count, loss of muscle mass, and erectile dysfunction. Thyroid disease is much more common in women, so men may not attribute symptoms unique to men as secondary to thyroid disease. However, men tend to have increased thyroid problems with age.  

The endocrine system is complex. A slight change in one hormone can have far-reaching consequences throughout the body. Testosterone levels decline at a rate of about one percent per year, beginning around the age of 30.

Because of the interrelationship between hormone functions, you may notice symptoms that seem unrelated. It can be difficult to diagnose low testosterone levels. Once your testosterone levels are low enough to cause symptoms, such as 

  • Low libido
  • Low energy
  • Few spontaneous erections
  • Decreased muscle mass

The diagnosis may be clear. 

However, most men want to take whatever steps possible to prevent these symptoms from developing. You can support your body’s ability to make testosterone by getting enough sleep, eating nutrient-dense foods with healthy sources of protein and fats, and engaging in physical activity that improves strength, balance, and cardiovascular fitness. 

If these lifestyle changes are not enough to reverse or at least improve your symptoms, consider having your testosterone levels tested. 

The Relationship Between Thyroid Hormone And Testosterone Hormone

It is also important to determine whether an abnormal thyroid hormone level is causing your symptoms. Sexual dysfunction affects 59-63 percent of men with hypothyroidism and 48-77 percent of men with hyperthyroidism (Gabrielson et al., 2019).

The thyroid gland is a butterfly-shaped gland on the front of the neck. It releases two hormones, triiodothyronine (T3) and thyroxine (T4). These hormones regulate:

  • Metabolism
  • The nervous system
  • The immune system
  • Muscle strength
  • Body weight
  • Temperature levels
  • Sleep cycles
  • Cognition
  • Heart and bone health
  • Cholesterol levels
  • Digestion
  • Reproduction 

Thyroid function also affects growth hormone production, cortisol (stress hormone) levels, glucocorticoid levels, and gonadal function (Merkle, 2004). It is very difficult to isolate the functions of one hormone from the rest. 

Can Thyroid Problems Cause Low Testosterone?

The thyroid gland is regulated by a negative feedback loop. When T4 levels are too low, the hypothalamus produces thyrotropin-releasing hormones (TRH), and the pituitary gland produces thyroid-stimulating hormone (TSH) to prod the thyroid to increase production. Conversely, if T4 is too high, TRH and TSH production is inhibited. 

A properly functioning thyroid gland produces just the right amount of thyroid hormone to meet the body’s needs. If too much thyroid hormone is produced, it is called hyperthyroidism. If too little is produced, it is called hypothyroidism. 


Hypothyroidism is a condition in which the thyroid gland does not produce enough thyroid hormone. Thyroid hormone production can be adequate for normal body function, inadequate or subclinical, which means that TSH levels are slightly above the upper range of normal but not enough to warrant a diagnosis of hypothyroidism. 


Symptoms Of Hypothyroidism (Too Low Thyroid): 

  • Weight gain
  • Dry skin
  • Fatigue
  • Feeling cold
  • Constipation
  • Depression
  • Muscle aches and stiffness
  • Hair loss
  • Enlarged thyroid
  • Low sex drive
  • Delayed ejaculation
  • Erectile dysfunction
  • Increased cholesterol
  • Loss of eyebrow hair 
  • Memory impairment

Potential Causes Of Hypothyroidism: 

  • Iodine deficiency (iodine is required to produce thyroid hormone) 
  • Hashimoto’s thyroiditis (autoimmune thyroid disease) 

The hypothalamus secretes gonadotropin-releasing hormone (GnRH). GnRH stimulates the anterior pituitary gland to produce luteinizing hormone (LH) and follicle-stimulating hormone (FSH). LH stimulates testosterone production in the testes.

Testosterone is transported through the bloodstream, primarily bound to the protein sex hormone-binding globulin (SHBG), though some can be carried by another protein called albumin. A small amount of testosterone, free testosterone, is not bound to a protein. 

Increased TSH levels due to hypothyroidism cause a decreased LH response to GnRH. Recall that LH stimulates the testes to produce testosterone. This abnormal response is associated with low testosterone levels. Men with hypothyroidism have low free testosterone levels. However, when thyroid hormone levels are normalized, testosterone levels return to normal as well (Meikle, 2004; Kumar et al., 1990).

Hypothyroidism can also cause an increase in prolactin levels, a hormone that stimulates milk production in nursing mothers. Increased prolactin levels can also lower testosterone levels (Chen et al., 2018). 

Subclinical hypothyroidism has been linked to lower testosterone levels and higher prolactin levels. However, more research is needed to determine the significance of this finding (Kumar et al., 2006). 


Hyperthyroidism is a condition in which the thyroid gland produces too much thyroid hormone. Grave’s disease, an autoimmune disorder, is often the cause of hyperthyroidism. The connection between hyperthyroidism and testosterone is less clear, but there is evidence that changes in thyroid hormone levels can affect how testosterone is delivered in the bloodstream.


Symptoms Of Hyperthyroidism (Too High Thyroid): 

  • Weight loss
  • Racing heartbeat
  • Feeling warm
  • Tremors
  • Feeling anxious, nervous, or irritable
  • Increased appetite
  • Difficulty sleeping
  • Fatigue
  • Enlarged thyroid
  • Low sex drive
  • Premature ejaculation
  • Diarrhea

Potential Causes Of Hyperthyroidism: 

  • Grave’s disease (an autoimmune disorder)
  • Thyroid nodules
  • Inflammation of the thyroid
  • Too much iodine in the diet (Melish et al., 199)

Men with hyperthyroidism have higher testosterone levels, higher sex hormone-binding globulin (SHBG) levels, and an increased LH response to GnRH (Meikle, 2004). 

High SHBG levels are associated with a drop in free testosterone levels. Men with hyperthyroidism may have changes in how the hypothalamus, pituitary, and testes interact, which may also cause symptoms (Hudson & Edwards, 1992).

Treatment Options

The first step is to have a thorough history and physical exam. After that, your healthcare provider may advise you to have your TSH and T4 levels taken to screen for thyroid disease. If your thyroid function is abnormal, the next step is to determine the cause and discuss treatment options. 

Once your thyroid hormone levels have been corrected, your doctor may test your testosterone levels. 

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The American Urological Society defines low testosterone (Low-T) as less than 300 nanograms per deciliter (ng/dl). Low testosterone levels can cause a low sex drive, decreased lean muscle, irritability, fatigue, erectile dysfunction, and depression.

  • Total testosterone level: Generally, two separate testosterone levels are obtained, with both levels taken before noon, as testosterone levels tend to naturally decrease later in the day.
  • Luteinizing hormone (LH): LH stimulates the production of testosterone in the testes. Abnormal levels may indicate a problem with the pituitary gland.
  • Blood prolactin level: Prolactin is a hormone that stimulates breast development and milk production in the female. Increased levels in the male may be a sign of a benign pituitary tumor, among other possible causes.

Total testosterone levels measure testosterone that is mostly bound to SHBG and albumin, whereas free testosterone measures unbound testosterone. 

Side effects can occur when testosterone is used incorrectly or at an excessively high level. Therefore, it is important to work with your healthcare provider to ensure that you can maximize the benefits of testosterone replacement therapy while minimizing the risks. 

While we strive to always provide accurate, current, and safe advice in all of our articles and guides, it’s important to stress that they are no substitute for medical advice from a doctor or healthcare provider. You should always consult a practicing professional who can diagnose your specific case. The content we’ve included in this guide is merely meant to be informational and does not constitute medical advice.

Can Thyroid Problems Cause Low Testosterone?

Leann Poston, M.D.

Dr. Leann Poston is a licensed physician in the state of Ohio who holds an M.B.A. and an M. Ed. She is a full-time medical communications writer and educator who writes and researches for Invigor Medical. Dr. Poston lives in the Midwest with her family. She enjoys traveling and hiking. She is an avid technology aficionado and loves trying new things.



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