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Senior man curling barbell with use of testosterone therapy to prevent muscle wasting

Do I Need Testosterone Replacement?

Worldwide, testosterone levels are declining and usually under diagnosed. Aaron E. Katz, MD, Chairman of Urology at Winthrop University Hospital in Mineola, New York, discusses the prevalence of testosterone deficiency and provides three steps to follow with your doctor in determining if testosterone supplementation is right for you.

Scientifically reviewed by Dr. Gary Gonzalez, MD, in August 2023. Written by: Aaron E. Katz, MD.

Aaron E. Katz, MD

Aaron E. Katz, MD

Q: I am a 61-year-old man in generally good health, but I’ve been experiencing some worrisome symptoms lately. I just don’t seem to have the vigor that I once had, I feel fatigued much of the time, as though my mind were in a fog, and my enthusiasm for work and recreation isn’t what it once was. Could I be suffering from testosterone deficiency? If so, is testosterone replacement safe and effective at my age? What tests should I undergo? What are the risks of the therapy?

A: You ask some important questions, ones that I hear all the time from men in my integrative urology practice. Let’s see if we can shed some light on this important issue.

First, testosterone deficiency (or “low T,” as some TV ads put it) is real. There’s been a gradual decline in average testosterone in men around the world over the past few decades. In industrialized nations, as many as 10% of men have testosterone below the “normal” level; that number rises to 15 to 30% in diabetic or obese men.1-3

Testosterone deficiency is unfortunately under-diagnosed; too many men have their symptoms written off as “normal aging” or depression, when in fact there may be a chance to intervene favorably.1 In fact, fewer than 10% of men with testosterone deficiency receive treatment.1

For reasons not yet entirely worked out, we see testosterone levels begin to decline in adult men at about the age of 30, after which levels fall about 1% per year. So by the time you are 61, your testosterone levels are likely to have fallen nearly a third compared to what they were in your youth.

Naturally, not all men experience testosterone decline at precisely the same rate, but when levels drop as they may have in your case, it’s not at all unusual for there to be some changes that you can see, and also that you can feel.

Although testosterone is produced by both men and women, it is traditionally thought of as a male hormone, and in men, about 90% of it is produced in the testes. We see the effects of testosterone in men after puberty in the form of so-called secondary sex characteristics: facial and body hair, a deepening of the voice, clear muscle definition, etc.

So, with decreasing testosterone levels, the changes you may see have to do with some of those features: diminished muscle mass or definition, decreased strength, and so on. Men in my practice frequently complain that their workouts aren’t as effective as they once were; it takes them longer and they have to work harder to maintain their “buff” look.

Widespread Influence of Testosterone

Businessman sleeping in park 

But testosterone is also a neurohormone, with profound effects on our behavior and mood. So the things you may feel with declining testosterone are a decrease in sex drive and performance, sleep disturbances, including trouble getting to sleep or staying asleep, loss of concentration, irritability, and a general loss of drive for work and play, just as you report. I often hear from men whose testosterone levels are low that they just don’t find themselves turning heads on the street the way they used to.

Your comment about “mind fog” is important. This is indeed often a complaint I hear from men with low testosterone. On the other hand, men with prostate enlargement (benign prostatic hypertrophy, or BPH) may suffer from multiple sleep interruptions at night, when they need to get up to urinate frequently. Those disruptions of a normal sleep cycle may also be contributing to your fatigue. If you think you might be suffering from BPH, it is important that you have your prostate evaluated before beginning testosterone treatment.

Step 1: Modify Lifestyle Factors That Affect Testosterone Levels

Some other factors might be influencing your experience as well, entirely unrelated to testosterone levels: are you taking other medications that could produce somnolence or a sense of weakness? Do you have an abnormality in blood chemistry that might explain it? Are you having exceptional stress in your life? Any of these (and many others) could explain your symptoms, but most of them can also be causes of falling testosterone levels.

And there are plenty of modifiable things that could cause your testosterone to drop. Obesity is one of the best known; fat tissue contains enzymes that convert testosterone to estrogen, robbing you of your male hormone and raising levels of your female hormones (both men and women need to have both testosterone and estrogen for normal function, but testosterone is predominant in men, estrogen in women).2 With obesity comes the metabolic syndrome and diabetes, two additional known risk factors for testosterone deficiency.2,4

Smoking is another known factor that can speed a man’s declining testosterone levels, as is excessive alcohol consumption.5,6 And stress can suppress them substantially.7,8

So, before considering testosterone therapy, I always encourage men to change what they can in terms of these risk factors. That usually means losing some weight, and always means quitting smoking, even if that requires short-term drug therapy. Cutting alcohol intake to not more than 1-2 drinks/day is also likely to be helpful.

One word about exercise: regular, mild exercise will help raise testosterone levels, but constant over-exertion can have precisely the opposite effect: levels can drop even further.9-12 Be sure your exercise regimen is not excessive; it’s best to do it under the supervision of a trainer or physician.

Step 2: The Medical Work Up

Once we’ve addressed all those risk factors, if symptoms persist, it is indeed time to consider testosterone replacement therapy. A visit to your doctor for a thorough history and physical exam is vital preparation for testosterone therapy. I don’t believe that anyone should embark on any kind of hormone replacement therapy without a physician’s guidance, so that means no ordering testosterone from websites promising sexual vitality and a youthful body!

At that office visit, your doctor will perform a rectal exam to estimate the size of your prostate, and to determine if you have any enlargement (the rectal exam is also a screen for prostate cancer). I won’t start testosterone replacement therapy in any man with a significantly enlarged prostate, because treatment could cause further, rapid enlargement of the prostate, which could block your urine flow. You might need to be started on one of the available drugs to relieve prostate enlargement before you can initiate testosterone therapy.

At your doctor’s office you’ll also provide a blood specimen to be tested for prostate specific antigen (PSA), as a further screen for cancer. I also perform an ultrasound of the prostate. This helps me standardize a man’s PSA level to get a more accurate idea of any potential cancer risk.

Finally, your blood will be tested for its testosterone and estradiol content. While there are several ways to measure testosterone, in my practice I simply use the total testosterone level. It is also important to check estradiol levels because many men with deficient testosterone over-convert testosterone to estradiol resulting in higher than desirable levels of estradiol. Men with higher levels of estradiol should begin an aromatase inhibitor at the same time as testosterone replacement therapy is initiated to prevent this conversion. Note that you don’t have to have been fasting prior to these blood tests.

Step 3: Time for Testosterone

Embryology sample and microscope  

So, assuming that, given your symptoms and a normal physical exam, your testosterone level comes back in the deficient range, we then have a number of options for treatment. Probably the most commonly-used therapy is a topical gel, which you would apply to your arms, abdomen, or legs— not your scrotum.

It’s important at this stage to emphasize patience! It can take weeks to months not only to achieve desirable levels, but also to begin to see and feel the results. And recognize that, since you have a cluster of symptoms, they may resolve at different rates.

Side effects of testosterone therapy are generally minimal and rare. A few men develop acne, while even fewer may experience breast enlargement, which is a sign that they are converting too much testosterone into estradiol, warranting the prescribing of an aromatase-inhibiting drug like anastrozole.

Perhaps the most significant effect of testosterone replacement therapy is that it will cause your testes, your normal source of testosterone, to dramatically reduce their own production of the hormone. That can mean shrinkage of the testes over time, as well as a decrease in sperm production. So, younger men, or any man interested in his fertility, should be aware that testosterone therapy could lead to infertility.

Conversely, a man who is past his reproductive years, and who gets good results from testosterone replacement, may find that he will need to continue treatment for life (or for as long as he desires the benefits). So long as the other side effects remain under control, this is a safe option.

Testosterone Therapy and Prostate Cancer

And that brings us to a final important question, namely, what is the impact of testosterone therapy on prostate cancer? Many prostate cancers are “androgen dependent,” that is, they require a certain level of testosterone in order to grow and survive. That, for many years, made physicians leery of starting replacement therapy for fear of triggering or promoting a malignancy.

More recently, however, we’ve learned that this is largely an unnecessary concern.13 While it could be potentially dangerous (and counterproductive) to start testosterone replacement in a man with active prostate cancer, we now know that in men with treated prostate cancer, whose PSA levels are stable, testosterone therapy is safe.


Testosterone deficiency in older men is a real and growing problem, though its symptoms often overlap with those of other conditions. That means a thorough history and physical exam is mandatory before considering testosterone replacement, as is a baseline measurement of testosterone. Losing weight, cutting back on drinking, and stopping smoking are non-invasive steps you can take to raise your testosterone levels naturally. Testosterone therapy, if indicated, is generally safe, easy to apply, and free of major side effects, but men should recognize that long-term testosterone therapy can produce infertility.

Since low testosterone is statistically associated with higher risks of a host of age-related diseases such as reduced longevity, risk of fatal cardiovascular events, obesity, muscle wasting, mobility limitations, osteoporosis, frailty, cognitive impairment, depression, Sleep Apnea Syndrome, and other chronic diseases,13 you may be doing yourself a favor far greater than simply reducing your troublesome symptoms.

If you have any questions on the scientific content of this article, please call a Life Extension® Wellness Specialist at 1-866-864-3027.

Aaron E. Katz, MD, is currently the Chairman of Urology at Winthrop University hospital in Mineola, NY. Dr. Katz has developed a patented blood test to detect micrometastatic circulating tumor cells in patients with prostate cancer that has not yet spread. The National Institutes of Health has awarded grants to Dr. Katz to support his research. Dr. Katz has become an international leader in the field of cryotherapy and ablation of small tumors within the prostate and kidney. Dr. Katz’s deep interest in herbal medicine research led him to found the Center for Holistic Urology at Columbia in 1998, where he has been a clinical investigator and managed several groundbreaking new cancer prevention clinical trials. In 2006, Dr. Katz was named the Vice Chairman of Columbia University’s Department of Urology. Dr. Katz has published over 100 scientific articles in peer-reviewed journals and has authored several chapters in urologic text books. His first book for the lay audience, Dr. Katz’s Guide to Prostate Health: From Conventional to Holistic Therapies (Freedom Press), was published in 2006. He is currently the host of “Katz’s Corner,” a Sunday morning radio show on WABC.


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