Testosterone is the primary sex hormone in men, and it is responsible for the development of many of the physical characteristics that are considered typically male. Women also produce the hormone in much smaller amounts. Testosterone, part of a hormone class known as androgens, is produced by the testicles after stimulation by the pituitary gland, which is located near the base of the brain, and it sends signals to a male’s testicles (or to a woman’s ovaries) that spark feelings of sexual desire.
The Role of Testosterone in Male Development and Health
In males, testosterone plays an important role in puberty, the time when a young man reaches sexual maturity and he can reproduce. The following changes typically happen during this life stage:
- The penis and testicles grow
- Facial, pubic, and body hair develop
- The voice deepens
- Muscles and bones become stronger
- Height increases
What Happens When Testosterone Levels Are Low?
Testosterone levels gradually drop in men as a natural part of aging. By age 45, it starts falling by about 1 percent a year, according to research published in the Journal of Clinical Endocrinology & Metabolism, but it is widely accepted that levels may start to decline when a man is in his thirties.
Lifestyle factors also affect testosterone production, including exercising too much or not eating a healthy diet.
How Can You Tell if Testosterone Levels Are High, Low, or Normal?
Your doctor can order a blood test to find out if your testosterone levels are in the normal range.
What Is Low Testosterone or “Low T”?
In some cases, low testosterone (also known as low T) may be caused by a medical condition known as hypogonadism, which occurs when the body does not generate normal amounts of the hormone. It happens when there is a problem with the testicles or the pituitary gland that creates an inability to produce normal amounts of testosterone.
Symptoms of so-called low T vary depending on the cause of problem and the age when it happens.
In men who are middle-aged and beyond, symptoms may include:
- Low energy and depressed mood
- Sleep disturbances
- Low sex drive
- Problems getting or maintaining an erection
- Low sperm count
- Loss of muscle and bone strength
Not all men with age-related low testosterone will experience any symptoms, and others aren’t bothered by them. Troubles with energy, sleeping and mood can also be caused by other issues like medication side effects or excessive alcohol use.
How Do Doctors Test for and Diagnose Hypogonadism?
Hypogonadism (as well as age-related low testosterone) is diagnosed with blood tests that measure the level of testosterone in the body. The Endocrine Society recommends testing for suspected low T with a total testosterone test. It may be performed in the morning when testosterone levels tend to be highest in young men, although this isn’t necessarily the case in older men. The test may be repeated on another day if the results show a low T level.
What Are the Options if Your Testosterone Levels Are Low?
Testosterone replacement therapy is currently only FDA approved for men who have been diagnosed with hypogonadism, but it’s also prescribed off-label for older men who take it in hopes that it will improve their libido. The use of testosterone therapy is increasingly common in the United States, with more than 2 million men receiving the therapy. Not every man benefits from taking testosterone supplements. Testosterone is available in different forms, including topicals such as gels, creams, and patches; injections; and pellets that are surgically placed directly beneath the skin.
What Are the Side Effects of Testosterone Replacement Therapy (TRT)?
Possible long-term effects of TRT have not yet been established, but there is scientific evidence to suggest it may have an impact on cardiovascular health, cancers of the prostate and breast, and sleep disturbances such as sleep apnea.
People who take testosterone should seek medical attention immediately if symptoms of a heart attack or stroke are present, such as:
- Chest pain
- Shortness of breath or trouble breathing
- Weakness in one part or one side of the body
- Slurred speech