What is Testosterone?
Testosterone is the male sex hormone that is made in the testicles. Testosterone hormone levels are important to normal male sexual development and functions.
During puberty (in the teen years), testosterone helps boys develop male features like body and facial hair, deeper voice, and muscle strength. Men need testosterone to make sperm. Testosterone levels generally decrease with age, so older men tend to have low blood testosterone levels.
What is Low Testosterone?
Some men have low testosterone levels. This is called Testosterone Deficiency Syndrome (TD) or Low Testosterone (Low-T). Deficiency means that the body does not have enough of a needed substance. Syndrome is a group of symptoms that, together, suggest a disease or health condition.
The American Urology Association (AUA) identifies low blood testosterone (Low-T) as less than 300 nanograms per deciliter (ng/dL). These symptoms or conditions may accompany Low-T:
- Low sex drive
- Reduced lean muscle mass
- Erectile dysfunction
- There are many other possible reasons for these symptoms, such as: opioid use, some congenital conditions (medical conditions you are born with), loss of or harm to the testicles, diabetes, and obesity (being overweight). See your doctor if you have any of these symptoms.
Why Testosterone Therapy (TT)?
You may need testosterone therapy (TT) if you have Low-T. Both the FDA and the AUA suggest that TT be used to treat conditions you are born with, such as Klinefelter syndrome.
You also may need TT if you harm or lose your testicles. If your testicles are removed because of a sickness such as cancer, you may need TT. Most men with Low-T (no matter what the cause) will be treated if they have both symptoms of Low-T and blood tests showing Low-T levels. Talk with your doctor if you feel that you may need TT.
TT may help you but it may have adverse (harmful) results. (See discussion of these side effects below.) The Federal Drug Administration (FDA) has said that testosterone drug labels should state that there is a risk for heart disease and stroke for some men using testosterone products. All men should be checked for heart disease and stroke before, and periodically while on, TT. The AUA however, on careful review of evidence-based peer review literature, has stated that there is no strong evidence that TT either increases or decreases the risk of cardiovascular events.
The FDA also was concerned when they found that men were being treated for Low-T due only to aging. There is ongoing research to determine more about TT in aging men. Your doctor will talk with you about the benefits and risks of TT and carefully consider how to treat your symptoms.
How Common is Low Testosterone in Men?
It is hard to know how many men among us have TD, although data suggest that overall about 2.1% (about 2 men in every 100) may have TD. As few as 1% of younger men may have TD, while as many as 50% of men over 80 years old may have TD. People who study the condition often use different cut-off points for the numbers, so you may hear different numbers being stated.
TD is more common in men who have diabetes or who are overweight. In one research study, 30% of overweight men had Low-T, compared to only 6.4% of those with normal weight. The same study found diabetes to be a risk factor for TD. In another study, 24.5% of men with diabetes had Low-T, compared to 12.6% of those without diabetes.