Male hypogonadism is defined as the underproduction of sperm or testosterone, or both, by the testes (also called testicles). Starting at puberty, the pituitary gland releases luteinizing hormone (LH), which stimulates the testicles to produce testosterone, the hormone responsible for male physical characteristics. In the testicles, follicle stimulating hormone (FSH) and LH also act together to stimulate the production of sperm.

Diagnosis of male hypogonadism begins with a medical history and physical examination. Many possible symptoms and signs may suggest low testosterone, or androgen deficiency, in adult men:

  • Incomplete sexual development
  • Reduced sexual desire (libido) and activity
  • Decreased spontaneous (night-time and morning) erections
  • Breast discomfort or enlargement
  • Loss of body hair, reduced shaving
  • Very small or shrinking testes
  • Inability to father children; low or zero sperm counts
  • Height loss, low bone mineral density, easily broken bones
  • Reduced muscle bulk and strength
  • Hot flushes, sweats
  • Decreased vitality (low energy, excessive fatigue)
  • Mild depression

Blood tests determine whether testosterone levels are in the normal range. This is generally 300 to 1,000 ng/dL (10.4 to 34.7 nmol/L), but the normal range may differ depending on the laboratory that conducts the test. To diagnose low testosterone, a man generally needs to have more than one early-morning blood test. If his blood testosterone is repeatedly low, then tests of pituitary gland function, such measuring LH and FSH levels, must also be done.

Causes of male hypogonadism

Male hypogonadism can be primary (resulting from a problem with the testes) or secondary (resulting from a problem with the pituitary gland or hypothalamus and their release of LH and FSH), or a mix.

Speaking more generally, low testosterone can be caused by:

  • testicular injury (trauma, castration, radiation, or chemotherapy) or infection (mumps)
  • pituitary or hypothalamic tumors or diseases
  • hormonal disorders, such as high levels of prolactin (a hormone produced by the pituitary that lowers testosterone levels)
  • other chronic medical diseases such as HIV/AIDS; type 2 diabetes and obesity, liver, or kidney disease
  • some medications such as prednisone, or opiate pain medications
  • genetic conditions including Klinefelter syndrome, Kallmann syndrome, and Prader-Willi syndrome

Many older men have low testosterone levels and, in many cases, the cause isn’t known.

Treatment of male hypogonadism/androgen deficiency

Treatment with testosterone replacement therapy is recommended for men with consistently low testosterone levels and symptoms or signs of androgen deficiency. Men with one of the following should not be treated with testosterone replacement therapy:

  • Active (current) or a history of aggressive, high grade breast or prostate cancer
  • Suspected prostate cancer, based on a lump or hardness in the prostate or high PSA (prostate-specific antigen) level
  • A high number of red blood cells, untreated obstructive sleep apnea (long pauses in breathing during sleep and loud snoring), severe untreated enlargement of the prostate acausing difficulty urinating, or uncontrolled severe heart failure

The overall goal of testosterone hormone therapy is to increase testosterone levels from below the normal range to the middle of the normal range. Goals may vary from patient to patient but should include improving or maintaining the signs of masculinity (such as deep voice, beard growth, pubic hair), and improving sex drive and function,, mood and energy, muscle strength, and the amount of bone.

There are several ways to replace testosterone:

  • Injections into the muscle (usually every 2 weeks)
  • Patches (applied to skin once a day)
  • Gel or solution preparations (applied to skin once a day)
  • Buccal tablets (applied to the gums twice a day)
  • Pellets (implanted under the skin)
  • Pills (available in some countries outside the United States)

The way testosterone is given will depend on the patient’s preference and tolerance, and cost. The various types of testosterone therapy may have certain side effects. . Injections may be uncomfortable and linked to ups and downs in symptoms; patches may cause skin redness and rashes; gels may transfer testosterone to others who come into contact with the patient’s skin where the medication is applied; and buccal tablets may cause gum irritation.

It is not known whether long-term testosterone treatment increases the likelihood of prostate cancer. However, men who have a higher risk of developing prostate cancer, such as African American men and men older than age 45 who have close relatives with prostate cancer, andmen over age 50 generally should be monitored for prostate cancer during testosterone treatment.


Bradley Anawalt, MD
University of Washington

Alvin Matsumoto, MD
VA Puget Sound Health Care System

Last review: May 2013