Hypogonadism is a condition caused by disease or damage to the testes, hypothalamus, or pituitary gland that inhibits hormone secretion and testosterone production.

• Approximately four to five million men from ages 18 up to and including the elderly have lower than normal levels of testosterone, or testosterone deficiency, associated with hypogonadism.
  
• Symptoms associated with male hypogonadism include impotence and decreased sexual desire, fatigue and loss of energy, mood depression, regression of secondary sexual characteristics and osteoporosis. Hypogonadism is a risk factor for osteoporosis in men.
  
• Because the symptoms of testosterone deficiency associated with hypogonadism may vary or may be difficult to recognize, only an estimated five percent of men with testosterone deficiency are currently treated. Doctors can prescribe a blood test to measure testosterone levels.