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Low T and Hypothyroidism: What You Need to Know

Written by Author - Authors Medical experts of the National HRT Clinic - November 16, 2015


You may not know this, but your thyroid and testosterone levels may have an impact on one another. Thyroid issues are often thought of to be more of a concern for women, but that is not necessarily the truth. Men also need to know about Low T and hypothyroidism because there is a correlation between the two.

Before we get into the specifics of low testosterone and hypothyroidism, it might help to understand the functions of testosterone and thyroid hormones. Knowing how these chemical messengers impact bodily functions will also help you recognize if there is a problem.

The testes, ovaries, and adrenal glands supply the body with the testosterone that it needs to protect bone density, maintain brain functions, support metabolism, and strengthen heart health. Of course, as the primary androgen sex hormone, testosterone is also essential for sex drive and sexual activities. Infertility is frequently an issue for women and men with Low T.

Thyroid hormones impact every cell in the body – including those in the organs. You need adequate thyroid hormones to support body temperature, heartbeat, and muscle cell contraction. Thyroid hormones also support the rate at which you burn calories, move food through the digestive tract, and the replacement of dying cells.

The last thing you want is to have low testosterone with hypothyroidism. If that occurs, all the functions of testosterone and thyroid hormones may suffer.

As we continue this discussion about Low T and hypothyroidism, we will examine the following:

  • What is hypothyroidism
  • The symptoms of low testosterone
  • The symptoms of hypothyroidism
  • Important facts about low testosterone levels and hypothyroidism
  • Causes of Low T and hypothyroidism
  • How to treat testosterone deficiency and hypothyroidism

When testosterone and thyroid hormones are low, they can influence many critical functions in the body.

What Is Hypothyroidism?

Hypothyroidism is a condition that affects more women than men and occurs when the thyroid gland does not produce enough thyroid hormones. Eight times more women are likely to experience hypothyroidism than men, which is why there may also be a connection between Low T and hypothyroidism.

A delicate hormone production cycle begins with the hypothalamus sending thyrotropin-releasing hormone (TRH) to the pituitary gland. Once the pituitary receives stimulation from TRH, it produces thyroid-stimulating hormone (TSH) which enters the bloodstream and goes to the thyroid gland. In response, the thyroid secretes two hormones: triiodothyronine (T3) and thyroxine (T4) into the bloodstream. If the hypothalamus senses low T3 and T4 levels, it will increase TRH production. Conversely, when T3 and T4 blood levels are high, less TRH leaves the hypothalamus resulting in decreased thyroid hormone production.

In cases of primary hypothyroidism, TSH levels may increase, yet the thyroid gland cannot release more thyroid hormones into the bloodstream. Secondary hypothyroidism occurs when TSH levels decrease, and the thyroid does not receive the signals.

If a man has low T levels, hypothyroidism may also be present. Low T could trigger hypothyroidism, or it could be a consequence of thyroid disease. It is not always easy to determine which came first, especially in males.

Will low testosterone cause hypothyroidism in all men?

No, as you know, low testosterone is a relatively common condition as men age. However, because hypothyroidism is not as common in males, it does not always result from testosterone decline. We will talk more about the causes and occurrences of Low T and hypothyroidism in the section about important facts.

Hypothyroidism occurs when the thyroid does not produce enough thyroid hormones – T3 and T4.

How Do the Signs of Hypothyroidism Compare to Low T?

Knowing what to look for regarding Low T and hypothyroidism is important. You may feel fatigued, but if the only cause is that you have been working late for the last week, then you need not worry about hormonal imbalance.

To help you determine if you possibly have low testosterone or hypothyroidism, we list the most common symptoms of hypothyroidism and testosterone deficiency below:


  • Fatigue – feeling tired and sluggish is common, often resulting in reduced physical activity and exhaustion (may also cause excessive sleep without feeling rested)
  • Muscle Weakness – hypothyroidism causes the body to enter catabolism rather than anabolism leading to a breakdown of muscle tissue for energy resulting in weakness, muscle cramps, and aches
  • Metabolism and Weight Gain – difficulty losing weight due to metabolism causing the body to hold onto fat in the muscles and tissues
  • Temperature – inability to tolerate cold temperatures partly due to low metabolism from not burning calories
  • Hair Changes – thinning or loss of scalp hair, coarse dry hair due to hair follicle sensitivity to low thyroid levels
  • Depression – as with many other hormonal imbalances, depression is also linked to hypothyroidism (women may also find this contributing to postpartum depression)
  • Memory Loss – mental fog, forgetfulness, and poor focus are often present when thyroid hormone levels are low
  • Irritability – in addition to depression, mood changes such as anxiety and irritability are common
  • Constipation – hypothyroidism can decrease colon function, slowing down bowel movements and leading to constipation
  • Decreased Libido – sexual decline is possible in both males and females with hypothyroidism (men may also experience erectile dysfunction and infertility)
  • Skin Changes – pale, dry, rough skin may also be caused by loss of growth signals from thyroid hormone
  • Abnormal Menstrual Cycle – heavy bleeding and irregular periods are frequently linked to low thyroid hormone levels
  • Insomnia – lack of sleep or insomnia is possible with hypothyroidism

Maintaining proper hormonal balance is crucial to the body, as you can see from the symptoms of hypothyroidism above. In our next look at Low T and hypothyroidism, we compare the symptoms of low testosterone:

Low Testosterone:

  • Fatigue – loss of energy is common
  • Muscle and Strength – decreased muscle mass and strength is a telltale sign of Low T
  • Weight Gain – testosterone also plays a significant role in metabolism, often resulting in abdominal fat retention
  • Hair Loss – when testosterone converts into dihydrotestosterone (DHT), elevated DHT levels can impact the follicles and cause hair loss
  • Depression – testosterone was the original treatment for depression before anti-depressants as it acts on emotional androgen receptors in the brain
  • Memory Loss – testosterone also influences brain receptor cells that support a variety of cognitive functions, including learning, memory, and processing
  • Mood Changes – mood swings, irritability, anxiety, and increased stress are common
  • Decreased Libido – testosterone is the primary stimulator of sexual desire in men and women, supporting healthy erectile functions, vaginal lubrication, and fertility in males and females
  • Insomnia – when testosterone levels are low, cortisol levels increase, interfering with sleep and inhibiting testosterone production
  • Bone Loss – testosterone plays a role in maintaining proper bone mineral density so joint pains, height shrinkage, and stiffness are possible
  • Hot Flashes – both men and women may experience hot flashes and night sweats in response to changing estrogen and testosterone levels (testosterone converts into estrogen)

Low testosterone and hypothyroidism have many of the same symptoms, making it difficult to know the cause of symptoms without running diagnostic blood tests.

Testosterone and Thyroid Hormones – Important Facts

Autoimmune thyroiditis (also called Hashimoto’s disease) is the most common cause of thyroid gland hormone production decline. In this situation, the patient’s immune system causes a form of thyroid inflammation. Hypothyroidism can also be due to other medical treatments as well as hormonal imbalance. A tumor in the hypothalamus, pituitary gland, or thyroid gland could impact thyroid hormone production.

Many of the symptoms listed in the previous section are also associated with “normal aging” as many doctors like to call it. No, that is not what a hormone specialist will tell you. Normal aging does not lead to the severity of the signs we explained. As you can see, the symptoms are a result of changing hormone levels. They are as far from normal as you can get and should not be left untreated.

As with all hormonal imbalances, the best way to check for Low T and hypothyroidism is with blood analysis. In addition to standard blood count and lipid profiles, the doctor will also measure a variety of hormone levels including growth hormone via the insulin growth factor 1 test, and estradiol levels. Also included are:

  • Testosterone – total serum and free testosterone level tests
  • Thyroid Hormones – Free T4 (direct)
  • TSH – thyroid stimulating hormone to see if enough is going to the thyroid gland

Men will also have their PSA levels checked and may require FSH and LH measurements. Women may be tested for progesterone and DHEA-S levels depending on symptoms.

If there is a concern for hypothyroidism, the doctor may order a Free T3, Total T3, and Reverse T3 blood test.

Men with hypothyroidism may find that it leads to decreased testosterone levels. Progesterone and estrogen imbalance are more common in women with low thyroid levels. That does not mean, however, that they will not have Low T, as well. Progesterone is the precursor hormone to testosterone, so if it is low, testosterone may also be. Since the body uses testosterone to produce estradiol (estrogen), it is possible to have multiple hormonal imbalances at the same time. Insulin resistance, also common with Low T, is often present with hypothyroidism. That is why the hormone specialist will check multiple blood levels before making any determination of a diagnosis and ordering hypothyroidism and testosterone therapy.

The symptoms of hypothyroidism and low testosterone should never be brushed aside as normal aging.

Impact of Thyroid Hormone on Testosterone in Males

In addition to everything we have already discussed, there are some male-specific issues about Low T and hypothyroidism that are essential to explain.

    • Testes

The testicles produce testosterone and sperm, storing the sperm cells until they mature in a process called spermatogenesis. Thyroid hormones influence two different cell types in the testes. The first is the Sertoli cells which support the production of sperm cells. T3 hormone suppresses immature Sertoli cell marker expression while increasing the level of cell cycle inhibiting proteins. It also maintains inter-Sertoli cell junctions by regulating gap junction protein levels. T3 also stimulates androgen (testosterone) production in the Leydig cells.

    • Sperm

In addition to the influence on the Sertoli cells, thyroid hormone also impacts sperm morphology to aid in egg fertilization. Hypothyroidism can reduce sperm motility, interfering with its ability to move through the vaginal canal and up to the egg.

    • Reproductive Tract

Thyroid hormones exert action on the epididymis, affecting structure and secretory functions, as well as inhibiting the contractile activity of the vas deferens.

Hypothyroidism can directly impact a man’s fertility and testosterone levels.

What Can You Do to Treat Low T and Hypothyroidism?

It is essential to discuss options for hypothyroidism and testosterone replacement therapy if you test positive for either of both conditions. Because of thyroid hormone influence on the entire body, proper balance is essential. Men typically require a higher dose of thyroid hormone than women, just as they do with testosterone therapy. For most people, one pill in the morning – calculated to the dosage they need, is all that is necessary to treat hypothyroidism.

If you have both Low T and hypothyroidism, the doctor may or may not treat testosterone deficiency right away as increasing thyroid hormone may help boost testosterone production.

Women typically notice a change in hypothyroidism symptoms within 4 to 6 weeks. It may take 8 weeks or more for men to notice any changes. After that time, rechecking testosterone levels will also help determine if testosterone therapy is necessary.

Also, if you do not see significant results from hypothyroidism hormone therapy, testosterone replacement may be beneficial, especially if testosterone levels were extremely low. Some people do better with an initial course of treatment for both deficiencies.

Side effects from both thyroid and testosterone treatment are rare when prescribed by a hormone specialist. Any course of action is personalized to the individual’s unique needs. Thyroid medication is an oral pill. Testosterone treatment for men is typically an injection administered once every week or every two weeks depending on the type and dosage. Other testosterone preparations are also available. Women requiring testosterone therapy receive a transdermal cream compounded to the dosage they need.

For further information about hypothyroidism and Low T, please contact National HRT for a free consultation.

Treatment for low testosterone and hypothyroidism is safe and effective for men and women.

Medically reviewed by   Reviewers National HRT Staff - Updated on November 21, 2023

Please note that the information provided in this article is for informational purposes only and is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified healthcare provider with any questions you may have regarding a medical condition or treatment.


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