Medically reviewed by Judith Marcin, MD on April 19, 2017 — Written by Ryan Wallace and Kathleen Yoder
Testosterone is a hormone produced by the human body. It’s mainly produced in men by the testicles. Testosterone affects a man’s appearance and sexual development. It stimulates sperm production as well as a man’s sex drive. It also helps build muscle and bone mass.
Testosterone production typically decreases with age. According to the American Urological Association, about 2 out of 10 men older than 60 years have low testosterone. That increases slightly to 3 out of 10 men in their 70s and 80s.
Men can experience a range of symptoms if testosterone decreases more than it should. Low testosterone, or low T, is diagnosed when levels fall below 300 nanograms per deciliter (ng/dL). A normal range is typically 300–1000 ng/dL, according to the U.S. Food and Drug Administration. A blood test called a serum testosterone test is used to determine your level of circulating testosterone.
A range of symptoms can occur if testosterone production drastically drops below normal. Signs of low T are often subtle. Keep reading to learn the signs of low T in men.
#1. Low sex drive
Testosterone plays a key role in libido (sex drive) in men. Some men may experience a decline in sex drive as they age. However, someone with low T will likely experience a more drastic drop in their desire to have sex.
#2. Difficulty with erection
While testosterone stimulates a man’s sex drive, it also aids in achieving and maintaining an erection. Testosterone alone doesn’t cause an erection, but it stimulates receptors in the brain to produce nitric oxide. Nitric oxide is a molecule that helps trigger a series of chemical reactions necessary for an erection to occur. When testosterone levels are too low, a man may have difficulty achieving an erection prior to sex or having spontaneous erections (for example, during sleep).
However, testosterone is only one of many factors that aid in adequate erections. Research is inconclusive regarding the role of testosterone replacement in the treatment of erectile dysfunction. In a review of studies that looked at the benefit of testosterone in men with erection difficulties, nearly half showed no improvement with testosterone treatment. Many times, other health problems play a role in erectile difficulties. These can include:
- thyroid problems
- high blood pressure
- high cholesterol
- alcohol use
#3. Low semen volume
Testosterone plays a role in the production of semen, which is the milky fluid that aids in the motility of sperm. Men with low T will often notice a decrease in the volume of their semen during ejaculation.
#4. Hair loss
Testosterone plays a role in several body functions, including hair production. Balding is a natural part of aging for many men. While there is an inherited component to balding, men with low T may experience a loss of body and facial hair, as well.
Learn more: Hair loss and testosterone »
Men with low T have reported extreme fatigue and decrease in energy levels. You might have low T if you are tired all of the time despite getting plenty of sleep or if you’re finding it harder to get motivated to exercise.
#6.Loss of muscle mass
Because testosterone plays a role in building muscle, men with low T might notice a decrease in muscle mass. Studies have shown testosterone affects muscle mass, but not necessarily strength or function.
#7. Increased body fat
Men with low T may also experience increases in body fat. In particular, they sometimes develop gynecomastia, or enlarged breast tissue. This effect is believed to occur due to an imbalance between testosterone and estrogen within men.
#8. Decreased bone mass
Osteoporosis, or the thinning of bone mass, is a condition often associated with women. However, men with low T can also experience bone loss. Testosterone helps produce and strengthen bone. So men with low T, especially older men, have lower bone volume and are more susceptible to bone fractures.
#9. Mood changes
Men with low T can experience changes in mood. Because testosterone influences many physical processes in the body, it can also influence mood and mental capacity. Research suggests that men with low T are more likely to face depression, irritability, or a lack of focus.
Unlike women, who experience a rapid drop in hormone levels at menopause, men experience a more gradual decrease of testosterone levels over time. The older the man, the more likely he is to experience below-normal testosterone levels. Men with testosterone levels below 300 ng/dL may experience some degree of low T symptoms. Your doctor can conduct a blood test and recommend treatment if needed. They can discuss the potential benefits and risks of testosterone medication, as well.
Signs of low testosterone in men younger than 30 »
- Araujo, A.B., & Wittert, G.A. (2011). Endocrinology of the aging male. Best Practice & Research in Clinical Endocrinolog