Testosterone Deficiency (Hypogonadism)

Testosterone deficiency, or male hypogonadism, results when the body does not produce enough of the male sex hormone testosterone. Testosterone deficiency can occur at birth (congenital), during puberty or during adulthood. Millions of American men experience this condition, often after age 50, when testosterone production declines.

Testosterone is produced by the testes and regulated by hormones in the hypothalamus and pituitary gland. It plays an important role in male sexual and physical development and also maintains energy levels, fertility, sex drive and bone health in adults.


Male hypogonadism can be primary or secondary. Primary hypogonadism is caused by injury, disease or another factor affecting the testes. Secondary hypogonadism results from disorders or injuries affecting the centers in the brain that control hormones (hypothalamus or pituitary gland).

Risk Factors

Testosterone deficiency can be caused by:

  • Chemotherapy or radiation therapy
  • Aging — about 30% of men older than 75 experience low testosterone levels
  • Infections such as meningitis, syphilis, mumps
  • Undescended testes
  • Klinefelter's syndrome (an extra X chromosome causes underdeveloped testes)
  • Damage to the testes or brain caused by injury, tumors or surgery
  • Kallman syndrome — abnormal hypothalamus development
  • Some inflammatory disorders such as tuberculosis or sarcoidosis


Adult-onset hypogonadism can produce one or more of these symptoms:

  • Decreased libido (sex drive)
  • Erectile dysfunction (impotence)
  • Growth in breast tissue (gynecomastia)
  • Infertility
  • Muscle weakness or fatigue
  • Bone loss
  • Diminished growth or loss of body hair
  • Depression or other mood disorders

Congenital hypogonadism can cause undeveloped, ambiguous or underdeveloped genitalia. Onset during puberty can prevent normal male adolescent development, such as deepening of the voice, hair growth, and muscle and sex organ development.


Blood tests can determine the level of testosterone in your blood stream. These are usually taken in the morning, when testosterone levels are highest.


Primary hypogonadism often is treated with testosterone replacement therapy (TRT). The testosterone can be delivered through a number of different methods, each of which is usually effective at reducing symptoms and improving your energy and feeling of well-being. Cost, side effects and personal preference may determine which of the following is best for you:

  • An Implant— Testopel is a 5 minute office procedure where small pellets are implanted in the butt. These pellets increase testosterone to normal levels and slowly dissolve over 4-6 months at which time the procedure is repeated.
  • A gel — the testosterone is absorbed through the skin of your abdomen, upper arms, or thigh as the gel dries. You must avoid bathing and contact with others until the gel is dried. The gel is applied once daily.
  • Intramuscular injection — typically given every two weeks at home or in the doctor's office. Family members can learn to give the injections. Safe and effective, but testosterone levels may fluctuate between injections causing energy levels to rise and fall. This is the least ideal method of replacement.

Oral testosterone is no longer prescribed due to its association with severe liver problems and other difficulties.

Secondary hypogonadism that is caused by pituitary disorders may be treated with pituitary hormones. A pituitary tumor may be treated surgically or with radiation or medication.

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