Testosterone Levels, Low Testosterone Symptoms, and Testosterone Replacement Therapy

Estimated reading time: 9 minutes

An important question in clinical medicine is when to treat descending testosterone levels in men when there is no underlying cause other than advanced age.

Most men want to live to a ripe old age. But this could come at a price. We may have to depart with masculinity and vigor. Manliness may become a myth.

But, what if there was a simple way to retain the strength and hardiness of the 20s? Well, I guess most of us would at least give it a thought.


Could testosterone be the issue? We all know that testosterone is what makes men, men. The deep voice, the large muscles. It’s all about testosterone, isn’t it?

And, isn’t it true that testosterone levels start to fall in men by about 1% a year, beginning in the 40s?

And, isn’t low testosterone associated with weight gain, lack of energy, loss of muscle, and low sexual drive? Well, indeed it is.

So, could testosterone replacement therapy help us retain our hunkiness until old age?

Probably too good to be true.

Interestingly, there has been a dramatic increase in the use of testosterone therapy in healthy middle-aged and older men (1,2). The increased testosterone prescribing is primarily for age-related testosterone deficiency sometimes called andropause or age-related hypogonadism.

In other words, testosterone treatment is being used to correct a “normal” decline in testosterone levels that occurs with aging. Unfortunately, the evidence for the benefit of such therapy is somewhat limited (3).

Lately, the condition of “low T” among older men has been highlighted as an easily treated phenomenon. Direct-to-customer advertising (DTCA) has been guilty of encouraging the use of testosterone treatment for symptoms such as decreased energy and lack of sexual interest which have not always been proven to be caused by declining testosterone levels (4).

Furthermore, although the data are somewhat conflicting, some studies have suggested increased cardiovascular risk associated with testosterone replacement therapy (5).

However, although there is lack of general agreement among specialists, testosterone replacement therapy may be justified in selected cases. Hence, it is of utmost importance for clinicians and patients to understand when testosterone replacement therapy is appropriate and when it is not.

Testosterone Levels, Free Testosterone and Sex Hormone Binding Globulin (SHBG)

Testosterone is a hormone secreted by the testicles of males and in small amounts by the ovaries in females. It has several important biologic functions, particularly in men.

Testosterone is defined as an androgen. Andro means male in ancient Greek, and as an androgen, testosterone is responsible for the typical characteristics of the male human being such as the deep voice, the large muscle mass, and the facial and body hair.

Most of the testosterone in the blood is attached to two proteins: albumin and sex hormone binding globulin (SHBG).

Testosterone that is not attached to proteins is called free testosterone. 

The normal range for serum total testosterone in males is about 270 – 1070 ng/dL or 9 – 38 nmol/L. The normal levels in adult men are approximately 300 – 800 ng/dl or 10 – 27 nmol/L

There is a diurnal variation in testosterone levels, particularly in young men (highest values are at approximately 8 in the morning and lowest at about 8 in the evening). It is recommended that serum total testosterone should be measured between 8-10 in the morning.


Hypogonadism is a term that refers to a decrease in either of two important functions of the testicles; sperm production and testosterone production.

Hypogonadism may be caused by an abnormality of the testicles themselves (primary hypogonadism) or by a disorder of the pituitary or hypothalamus (secondary hypogonadism).

Hypogonadism may be congenital or may begin before puberty or during adulthood. The symptoms of hypogonadism depend on the age it develops.

The development of hypogonadism in adult males may cause erectile dysfunction, loss of libido, infertility, decreased muscle mass, decreased facial and body hair growth, development of breast tissue (gynecomastia), loss of bone mass (osteoporosis), and emotional changes. These symptoms will be reflected by low blood levels of testosterone.

Testosterone replacement therapy is used for the treatment of hypogonadism caused by the failure of the testicles to produce testosterone. Such treatment may increase well-being, sex drive, and erectile function, restore muscle strength and reduce bone loss.

Laboratory Findings in Hypogonadism

Males with hypogonadism have low levels of serum testosterone and free testosterone.

The two gonadotropins, luteinizing hormone (LH) and follicle-stimulating hormone (FSH), are produced by the pituitary. If testosterone production by the testicles drops, biofeedback mechanisms will respond by increasing the production of LH and FSH.

The serum levels of LH and FSH are above normal in primary hypogonadism. However, in secondary hypogonadism, serum concentrations of LH and FSH will be normal or low.

Testosterone Levels, Low Testosterone Symptoms, and Testosterone Replacement Therapy
The term age-related hypogonadism has been used to describe the clinical condition associated with declining testosterone levels in middle-aged and older men.

Age-Related Hypogonadism (Andropause)

Several studies show a declining serum total testosterone concentration with increasing age (6,7). It is estimated that serum testosterone levels decline at a rate of one percent per year after  the third decade of life (8).

SHBG concentrations increase gradually with age. As a result, there will be less free or biologically active testosterone available with increasing age.

The terms age-related hypogonadism and andropause have been used to describe the clinical condition associated with declining testosterone levels in middle-aged and older men.

The condition is also referred to as “late-onset hypogonadism.” It is typically diagnosed if, for no discernible reason other than older age, serum testosterone concentrations fall below the normal range and symptoms of low testosterone concentrations occur (9).

It has been suggested that the following symptoms may be associated with age-related hypogonadism:

  • a decline in muscle strength
  • reduced bone mineral density
  • a decline in sexual function
  • mood changes and depressive symptoms
  • anemia
  • central obesity
  • insulin resistance and metabolic syndrome

Nobody doubts that these symptoms may be present in men with hypogonadism due to pituitary or testicular disease. However, whether the same symptoms may occur with low testosterone levels associated with age has frequently been a matter of debate.

Another question is whether testosterone replacement therapy in men with age-related hypogonadism will improve these symptoms. If so, when and how should testosterone be administered?

Testosterone Replacement Therapy for Age-Related Hypogonadism

Clinical trials have reported some benefits of testosterone replacement therapy in older men. These include improved bone density, improved body composition, and improvement in physical function (8).

A relatively large randomized trial published 2016 suggests that testosterone replacement therapy for age-related hypogonadism in men aged 65 or older has beneficial effects on sexual function, depressive symptoms, mood, and possibly physical function (10).

However, in 2015 The US Food and Drug Administration (FDA) directed manufacturers of testosterone products to state in their labels that these products are approved only for men with low testosterone due to known causes (11).

Nonetheless, most experts today believe that testosterone replacement therapy may be recommended in the presence of clinical symptoms (decreased libido, low energy, depressive mood, osteoporosis or anemia) if low serum testosterone concentration has been documented on more than one occasion (12).

The cut-off value for low testosterone in middle aged or elderly men is usually considered to be less than 200 ng/dL (6.9 nmol/L).

The Potential Risks of Testosterone Replacement Therapy

Older men may be prone to testosterone dependent diseases. In other words, the presence of testosterone may promote disease.

Prostate cancer is an example of a prostate dependent disease. This is well illustrated by the fact that hormone analogs which lower testosterone levels are used for the treatment of prostate cancer.

Short-term trials have not shown that testosterone replacement therapy increases the risk of prostate cancer. However, more extensive trials of longer duration are needed to rule out an effect on prostate cancer risk.

Elevated red blood cell count is a common adverse effect of testosterone replacement therapy. The clinical implication of this phenomenon is uncertain. However, elevated red blood cell count has been associated with increased overall mortality and cardiovascular mortality in epidemiological studies (13).

Testosterone replacement therapy may reduce HDL-cholesterol which may be undesirable (14).

However, a recent meta-analysis did not support any causal role between testosterone treatment and adverse cardiovascular events. The authors concluded that this is especially true when hypogonadism is properly diagnosed, and replacement therapy is correctly performed (15).

Notwithstanding, testosterone replacement therapy should used with caution in patients with known clinically significant cardiovascular disease.

Testosterone Products 

Several testosterone products are available for the treatment of hypogonadism, age-related or not.

Oral preparations, although available, are seldom used due to lack of efficacy and risk of liver-related adverse effects.

Long-acting injections (Delatestryl, Depo-Testosterone) are often used. These can be administered every one to two weeks in most men and every three weeks in a few.

Extra-long acting injections (Nebido, Aveed) may be administered every 10-14 weeks.

Transdermal patches (Androderm, Andropatch) and gel (Testogel, Testim, Androgel, Fortesta, Axiron, Tostran) are popular but have to be administered daily.

The Bottom-Line

Serum testosterone levels decline with increasing age. This may negatively affect energy, sexual function, mood, physical strength, muscle mass, and bone mineral density in some middle-aged and older men.

Testosterone replacement therapy in older men with low testosterone levels (less than 200 ng/dL (6.9 nmol/L)) may improve sexual function, mood, depressive symptoms and possibly physical function.

Other causes of hypogonadism such as testicular or pituitary disease should be excluded before treatment is initiated.

Testosterone replacement therapy may make prostate cancer worse. Hence it is important to screen for prostate cancer before testosterone treatment is initiated and patients should be monitored for signs of the disease during treatment.

Increased red blood cell count represents the most common adverse event related to testosterone replacement therapy. 

Testosterone replacement therapy should be used with caution in patients with known clinically significant cardiovascular disease.

The article was initially published in 2017.

It was revised, updated and republished on March 22, 2022.


11 thoughts on “Testosterone Levels, Low Testosterone Symptoms, and Testosterone Replacement Therapy”

  1. “The target serum testosterone concentration during treatment in these men should be lower than that for young men, thus in the range of 300-400 ng/dL (10.4-13.9 nmol/L).”

    Absolute BS! I’m 63 – on TRT – use 40 mgs 2x/week subQ injections – last blood work – total testosterone was 992 ng/dL – drop me to the mid 300’s amd I will suffer.

    • I wouldn’t call it BS Charles.
      This is a general recommendation. Different targets may be appropriate for some individuals. That’s up to the treating clinician to decide.
      General recommendations have to account for the fact that the risk of testosterone dependent diseases increases with higher doses.

  2. At about age 54, I was treated with two courses of a Prednisone dose pack for a Brachial plexus neuritis. After that, my energy levels fell, strength began to wane, overuse symptoms began appearing. I sought E&M at Dr Jerry Mixon’s Longevity Medical Clinic, and found my free testosterone, DHEA, and Pregnenolone was low. (Perhaps it was already low, but I wonder if the steroid dose packs blocked the pathway from DHEA to testosterone, and began converted it to Estradiol–which is actually a treatment protocol performed at fertility clinics on some women with higher testosterone levels who are having trouble conceiving.) Lab tests measured the entire cascade, and I was placed on oral Pregnenolone, DHEA, and transdermal testosterone in Versabase, which was to be washed off nightly. I also was tested for serum levels of Vitamin D found to be in the 20-30s. Initially, I was aromatizing, so I was given minute doses of Arimadex. I was also told to take a few supplements, such as mixed tocopherols, supportive plant sterols for the prostate, minerals such as zinc, chromium, and magnesium/calcium. My levels came up, my energy and my creativity returned, and was able to return to exercise without injury. BMI dropped, I dropped the Arimidex and people look at me now and ask how do I stay in such great shape (at 66).
    Like the disaster that occurred with women being treated with conjugates of equine hormones, improper application of androgens CAN be less effective and do harm. Many of my patients enter my office and tell me their PCPs prescribed them Androgel, told them to rub it on their genitals, and “see how it goes”. No subsequent testing for aromatization. Or worse, they are given shots, creating totally non-physiologic rises and subsequent drops in levels. No consideration that application of testosterone may cause reduction in DHEA and Pregnenolone, and then a subsequent rise in cholesterol, which was initially noted to be seen at Longevity, until the complete pathway was evaluated and adjusted. The observation that testosterone dependent diseases increases with higher doses must be discussed in light of the method of application, especially since young adult males with high levels of the sex hormone cascade are not dropping from CVD and prostate cancer.
    The FDA’s primary role is the safeguarding of the pharmaceutical industry. The agency is a revolving door between the industry and agency. Bio-identical HRT threatens profits.

  3. Simple, cheap way to increase free testosterone is the supplement Boron. Use topical progesterone cream to prevent the conversion to estrogen (and protect your prostate). Also lower your estrogen levels by using the supplement DIM and/or consuming more fiber and cruciferous vegetables.

    • Yes. Boron is significant for bone density as well, as you probably know. A stumbling block to increasing free testosterone levels is aromatization of the testosterone in belly fat.

  4. I agree that a large number of healthy men have testosterone levels in the blood 5-20%(check here) below the accepted normal values, so it is very difficult to draw a clear line between a hypogonadal and normal status of the body. Moreover, the threshold level of the hormone at which a man begins to show symptoms of hypogonadism is very individual and varies from extremely low values to a value exceeding the lower limit of normal values for young men.
    The only way to find out if you need a Hormone Replacement Therapy is to contact highly qualified doctors who can always help you.
    They can understand what is the chain broken down hormones to assess hormonal function. Not only the built-up sex hormones – testosterone, progesterone, and estrogen-but also the adrenal and thyroid hormone. It is necessary to evaluate and metabolites of hormones, which are often more active than the hormones themselves.
    Please, do not self-medicate, and seek professional advice!

  5. Obesity is a huge burden on the body and primarily on the cardiovascular system. It is estimated that a person with a normal weight of 75 kg when traveling 1 km at a speed of 75 m per minute consumes about the same energy as is required to carry the same distance and with the same cargo speed of 19 kg. (And imagine how hard it is for such people to do some kind of physical work.
    Also read this article, it will be a useful addition http://www.business-opportunities.biz/2018/05/05/business-project-college-homework/.

  6. What an incredibly negative article. Just on one subject alone, Ca of the prostate, the author should read Dr. Morgentaler’s repudiation of the increase in Ca incidence.
    Also, why do you say that an increase in RBCs is an adverse event? There is no increase in platelets or other clotting factors and much of the world’s population lives at altitudes where high levels are normal and athletes train at altitude to achieve the elevation. Who came up with a “normal” of 200?
    You have written some insightful articles in the past but your bias is showing in this one.

    • Thanks for the comment Dr. Disiere.
      I certainly didn’t mean for the article be for or against testosterone treatment. What I wanted to do was to highlight factors that I believe are important to consider when deciding who to treat or not.
      However, I agree with you that the importance of testosterone induced increase in RBC is unclear. It has certainly been implicated that it may increase cardiovascular risk. The American Urological Association (AUA) recently (2018) issued a policy statement stating that, based upon current evidence, definitive answers on the cardiovascular risks of are not currently available.
      With regards to prostate cancer I wrote that it is important to screen for the disease before testosterone treatment is initiated and patients should be monitored for signs of the disease during treatment. Does that sound unreasonable?
      My sincere thanks for reading my blog and sharing your thoughts. It is highly appreciated.

  7. Besides, the edge level of the chemical at which a man starts to show side effects of hypogonadism is exceptionally individual and differs from very low qualities to a worth surpassing the lower furthest reaches of ordinary qualities for young fellows.
    The best way to see whether you want a Hormone Replacement Therapy is to contact exceptionally qualified specialists who can continuously help you.

  8. i for one believe obesity has contributed much to this and we working longer hours and family responsibilities have not created time for us to get to the gym and exercise. i am a good example of the paragraph above. So besides the age since its mentioned more frequently what others symptoms are there to look oy for that were not listed?


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