Testosterone is the most important sex hormone that men have. It is responsible for the typical male characteristics, such as facial, pubic, and body hair as well as muscle. This hormone also helps maintain sex drive, sperm production, and bone health. The brain and pituitary gland (a small gland at the base of the brain) control the production of testosterone by the testes.
In the short term, low testosterone (also called hypogonadism) can cause:
Over time, low testosterone may cause a man to lose body hair, muscle bulk, and strength and to gain body fat. Chronic (long-term) low testosterone may also cause weak bones (osteoporosis), mood changes, less energy, and smaller testes. Signs and symptoms (what you see and feel) vary from person to person.
During a physical exam, your doctor will examine your body hair, breasts, penis, and the size and consistency of the testes and scrotum. Your doctor may check for loss of side (peripheral) vision, which could indicate a pituitary tumor, a rare cause of low testosterone.
Your doctor will also use blood tests to see if your total testosterone level is low. The normal range is generally 300 to 1,000 ng/dL, but this depends on the lab that conducts the test. To get a diagnosis of low testosterone, you may need more than one early morning (7–10 AM) blood test and, sometimes, tests of pituitary gland hormones.
If you have symptoms of low testosterone, your doctor may suggest that you talk with an endocrinologist. This expert in hormones can help find the cause. Be open with your doctor about your medical history, all prescription and nonprescription drugs you are now taking, sexual problems, and any major changes in your life.
Testosterone replacement therapy can improve sexual interest, erections, mood and energy, body hair growth, bone density, and muscle mass. There are several ways to replace testosterone:
There are potential risks with long-term use of testosterone. You should discuss with your physician how to monitor for prostate cancer and other risks to your prostate. Men with known or suspected prostate cancer, or with breast cancer, should not receive testosterone treatment.
The Hormone Health Network is the public education affiliate of the Endocrine Society dedicated to helping both patients and doctors find information on the prevention, treatment and cure of hormone-related conditions.
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