What Every Man Needs To Know About Testosterone Replacement Therapy

Michael S. Irwig, MD, FACE

Male hypogonadism, which refers to either inadequate production of testosterone by the body and/or sperm by the testes, may be diagnosed when a low blood level of testosterone is detected. This hormone is the main sex hormone in a male and plays a key role in building muscle mass and bone density, reducing body fat and improving sex drive.

Several decades ago testosterone was rarely measured in men unless there was an obvious reason to do so, for example, either not going through puberty or exhibiting signs of fertility problems, or for symptoms such as fatigue, low sex drive or erectile dysfunction. Over the past decade, however, testosterone testing has become more commonplace, driven in part by an aging population, more precise tests and, arguably, a proliferation of so-called “low-T clinics.” Plus, makers of testosterone products have been heavily advertising their products, thus increasing awareness of the hormone and available treatments.

If you’re one of the millions of men who had a blood test that revealed low testosterone levels, you may be asking yourself (and your physician) if testosterone supplementation is necessary. You may also be asking about the differences between the many and varied testosterone products on the market.


First, a note about the science: There are several different types of testosterone tests performed by laboratories. Most doctors start by ordering a total testosterone and/or a free testosterone test. Much of the testosterone in the blood is bound to a protein called sex hormone binding globulin (SHBG). Free testosterone is not bound to protein and is easily used by the body. Plus, free testosterone can help provide more information when total testosterone is low.

The tricky thing to keep in mind is that it is unclear whether the total or free testosterone is the better test at assessing a man’s “androgen status”; an androgen is any of a group of hormones that primarily influence the growth and development of the male reproductive system.

To make things more complicated, it is possible to have a normal level of one type of testosterone and a low measurement of another. For example, many overweight or obese men have low levels of total testosterone, but normal levels of free testosterone. This often relates to differences in proteins that are bound to testosterone, such as SHBG.

And different labs establish their own “normal range” for testosterone such that one lab may report a range of 241-827 ng/dL (nanograms per deciliter), whereas another lab can report a normal range of 348-1197 ng/dL. For this reason, there is not one magic number that separates normal from low testosterone.

Regardless of which test is used, the diagnosis of male hypogonadism generally requires confirming one low level with a second test, as testosterone levels fluctuate during the day. Your doctor will likely request that you have your testosterone level checked with a blood test performed in the morning when levels tend to be at their highest.


If you elect to undergo testosterone supplementation, it’s important to note that the decision can be tricky and should be individualized, as there is no “one-size-fits-all” approach. Not all men with symptoms and low testosterone levels require treatment with testosterone. For example, an obese man may choose to lose weight, which in turn can increase his own production of testosterone. Similarly, a man who is not getting much sleep can increase his sleep duration to seven-to-eight hours per night to enhance testosterone production. When a doctor recommends testosterone therapy, the decision should be based upon the individual’s signs and symptoms, blood levels of testosterone, age and other medical conditions. For this reason, men with abnormal testosterone results are advised to discuss their results with an endocrinologist or other physician who has expertise in the area.

Unfortunately, it is often difficult to predict whether a man’s symptoms (such as low sex drive or fatigue) are related to his low testosterone levels or another malady. For this reason, many men are prescribed a three-to-six-month trial of testosterone therapy. For men who experience an improvement in symptoms, it is often reasonable to continue the therapy. For those whose symptoms do not show a marked improvement, it is often best to stop the therapy as their symptoms are likely related to something other than testosterone.

A Note Of Caution

You should not receive testosterone therapy if you have a contraindication such as prostate cancer, breast cancer, a high red blood cell count, uncontrolled heart failure or untreated severe sleep apnea. And men with lower urinary tract symptoms due to an enlarged prostate may experience a worsening of symptoms, as testosterone can cause the prostate to enlarge further.

Finally, testosterone is not approved to increase athletic ability or strength or for anti-aging purposes.

Therapy Options

There are a variety of different testosterone products approved by the U.S. Food and Drug Administration (FDA) for male hypogonadism. You may be wondering which product is the best. The correct answer is that that there is no right answer. Imagine that you need to travel from Washington, D.C. to New York City. Some people may prefer to fly, others to take a train and others to take a bus. While all methods can successfully get you to where you need to go, each method has its own advantages and disadvantages. The same pros and cons apply to testosterone products. Which formulation you choose will likely depend on how it is taken, how often it is taken, potential side effects and your insurance co-pay or out-of-pocket cost. Currently a pill form (oral) of testosterone is not available in the United States, although it is available in some other countries.

To help you compare products, here is a summary table of the testosterone options:

Type Route How often Considerations
Injections Intramuscular (self-administered) Every 1-3 weeks - Pain at injection site
- Fluctuating levels of testosterone
Injections Intramuscular (given at doctor’s office) Every 10 weeks - Pain at injection site
- Need to wait at office for 30 minutes after injection
Gels Topical (skin) Daily - Avoid skin-to-skin contact with a woman or child if the gel has not dried
Patch Topical (skin) Daily - Skin rash/irritation is common
Topical solution Topical (skin) to armpit Daily  
Pellets Implanted into fat under skin Every 3-6 months - More invasive with an incision in skin
- Infection is rare
- Bleeding is rare
- Cannot easily adjust dose
Nasal spray Nose 2-3 times/day - Nasal irritation/congestion
Buccal tablets Applied to gums 2 times/day - Gum irritation
- Seldom covered by insurance


Men on testosterone therapy need regular follow-up visits to monitor blood levels of testosterone, red blood cell count and PSA (prostate-specific antigen). A prostate exam may also be performed in men over age 40. Sometimes testosterone treatment needs to be stopped or the dose lowered if the blood cell count rises too high.

There is still spirited debate in medical circles over who needs testosterone replacement treatment, especially those who do not have laboratory-confirmed hypogonadism or certain medical conditions. Plus, the risks and benefits of taking testosterone for many years are not known, because large, rigorous studies haven’t yet been completed. While the perceived potential of testosterone therapy may seem enticing if you’re feeling tired or your libido is diminishing, there are a lot of misconceptions about what the treatment can and can’t do for you...and starting the therapy is a serious decision. Do so only on after receiving expert medical advice from a qualified physician.