Testosterone is a naturally occurring steroid hormone that is responsible for the development of male sex organs in the fetus and the changes that occur in men’s bodies during puberty.
In adulthood, testosterone is important for sperm production, maintaining muscle strength, and sex drive. Testosterone is produced primarily by the testes in response to hormonal signals from a part of the brain called the hypothalamus and the pituitary gland, which sits just below the hypothalamus.
Certain conditions are known to cause very low testosterone levels, which can lead to symptoms such as fatigue, lack of motivation, depressed mood, erectile dysfunction, and infertility. There is general agreement that these symptomatic men benefit from testosterone replacement. These conditions include:
- Men born with a poorly functioning hypothalamus or with certain genetic conditions may have extremely low levels of testosterone.
- Tumors, trauma, surgery or radiation of the pituitary gland can disrupt normal pituitary signals and lead to low testosterone.
- Hemochromatosis, a disease in which the body stores too much iron, and HIV infection can also cause low testosterone levels.
- Some medications can lead to profound declines in testosterone production, including certain medications used to treat prostate cancer and opioids such as morphine and methadone.
- Severe infections, injuries or loss of the testicles can also result in insufficient testosterone production. Many of these men will experience a significant improvement in quality of life with appropriate testosterone replacement but require careful monitoring.
In the absence of any of these conditions, men’s testosterone levels naturally decline gradually after the age of 30. Is this a normal process or is this decline a true disease? Do some older men benefit from testosterone replacement? Is testosterone replacement safe? Despite the lack of high quality studies designed to answer these questions, testosterone prescriptions for low testosterone associated with aging have skyrocketed in recent years, as has direct-to-consumer advertising for testosterone replacement . Fortunately, the ongoing results of a series of clinical trials supported by the National Institutes of Health will help answer some of these questions.
Men with low testosterone levels may be more likely to develop prostate cancer, heart disease, diabetes, sleep apnea and osteoporosis. However, testosterone replacement may not prevent any of these associated conditions. The long-term safety of testosterone replacement in older men is not well-established. Testosterone replacement therapy usually results in infertility, and can lead to other issues, including acne, breast tissue growth, blood thickening, and sleep apnea.
The symptoms of low testosterone, such as low libido and low energy, can be caused by many other problems including stress, lack of sleep and lack of exercise. If you suffer from these symptoms, consider trying regular exercise and ask for help managing stress and establishing healthy sleep habits. If these changes are not enough, talk to your doctor.
Peter Holoch, MD, is a urologist at the University of Vermont Medical Center and Associate Professor at the Larner College of Medicine at UVM.