What is the role of testosterone in men’s health?

Testosterone is an important sex hormone in men. 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:

  • A drop in sex drive
  • Poor erections
  • Low sperm count
  • Enlarged breasts

Over time, low testosterone may cause a man to lose body hair, muscle bulk, cause weak bones (osteoporosis), low red blood cells and smaller testes. Signs and symptoms (what you see and feel) vary from person to person.

What causes low testosterone (hypogonadism)?


  • Testicular injury (trauma, castration) or infection
  • Radiation or chemotherapy treatment for cancer
  • Some medications, such as opiate painkillers and corticosteroids (eg, steroid injections)
  • Hormone disorders (pituitary tumors or diseases, high levels of prolactin)
  • Chronic diseases, such as liver and kidney disease, obesity, sleep disorders, type 2 diabetes, and HIV/AIDS
  • A genetic condition (Klinefelter syndrome, hemochromatosis, Kallmann syndrome)
  • Anabolic Steroid

How is hypogonadism diagnosed?

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. Your doctor will take a thorough history of your symptoms and then complete a physical exam, including your body hair, breast tissue, and the size and consistency of the testes and scrotum.

Your doctor will also use blood tests to see if your total testosterone level is low. The normal range depends on the lab that conducts the test. To get a diagnosis of hypogonadism, you need at least two early morning (7–10 AM) blood tests that reveal low testosterone in addition to signs and symptoms typical of low testosterone. The cause of hypogondism can be investigated further by your doctor. This might include additional blood tests, and sometimes imaging such as a pituitary MRI.

How is hypogonadism treated?

Improvement of testosterone levels can improve sexual concerns, bone health, muscle and anemia (low red cells in the blood).  
Hypogonadism can resolve once the underlying cause is treated. However, if this is not possible, testosterone therapy might be needed (determined by an endocrinologist).

  • Gel or patches that you put on your skin
  • Injections (shots)
  • Tablets that stick to the gums
  • Pellets inserted under the skin
  • Pills (recently approved in the US)
  • Sometimes a medication called clompihene citrate is used to treat hypogonadism but this is not FDA approved for this indication. A thorough discussion is needed with your doctor

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 therapy. You should also talk to your doctor about the risks of testosterone therapy if you have, or are at risk, for heart disease or stroke. In addition, if you are planning fertility, you should not use testosterone therapy.

Other possible risks of testosterone treatment include:

  • Decreased sperm production
  • A high red blood cell count
  • Acne
  • An increase in prostate size
  • Sleep apnea—the occasional stopping of breathing during sleep (rarely)
If you are treated with testosterone, your doctor will need to see you regularly, along with blood tests.

Questions to ask your doctor

  • What is the cause of my low testosterone?
  • Is testosterone replacement an option for me?
  • When should I get my testosterone level retested?
  • Should I see an endocrinologist or urologist?