Testosterone is a hormone produced by the testicles and is responsible for the proper development of male sexual characteristics. Testosterone is also important for maintaining muscle bulk, adequate levels of red blood cells, memory, bone growth, sense of well-being and sexual function.

Inadequate production of testosterone is not a common cause of erectile dysfunction; however, when ED does occur due to decreased testosterone production, testosterone replacement therapy may improve the problem.

As a man ages, the amount of testosterone in his body gradually declines. This natural decline starts after age 30 and continues throughout life. Other causes of lowered testosterone levels include:

• Injury, infection, or loss of the testicles.
• Chemotherapy or radiation treatment for cancer.
• Genetic abnormalities such as Klinefelter's Syndrome (extra X chromosome).
• Hemochromatosis (too much iron in the body).
• Dysfunction of the pituitary gland (a gland in the brain that produces many important hormones).
• Inflammatory diseases such as sarcoidosis (a condition that causes inflammation of the lungs).
• Medications, especially hormones used to treat prostate cancer and corticosteroid drugs.
• Chronic illness.
• Chronic kidney failure.
• Liver cirrhosis.
• Stress.
• Alcoholism
• Chronic pain and use of narcotics for pain contol.
• HIV and AIDS

The significance of age-related testosterone decline is controversial and poorly understood.

Without adequate testosterone a man may lose his sex drive, experience erectile dysfunction, feel depressed, have a decreased sense of well-being, and have difficulty concentrating.

• Decrease in muscle mass, with an increase in body fat and weight gain
• Changes in cholesterol levels.
• Decrease in hemoglobin and possibly mild anemia.
• Fragile bones (osteoporosis).
• Decrease in body hair.
• Changes in cholesterol levels and lipid levels.

The only accurate way to detect the condition is to have your doctor measure the amount of testosterone in your blood. Because testosterone levels fluctuate throughout the day, several measurements will need to be taken to detect a deficiency. Doctors prefer, if possible, to test levels early in the morning since this is when testosterone levels are at their highest.

Testosterone deficiency can be treated by:

• Intramuscular injections, generally every two or three weeks
• Testosterone patch worn either on the body or on the scrotum (the sac that contains the testicles)
• Testosterone gel
• Mucoadhesive material applied above the teeth twice a day
• Injectible pellets

Each of these options provides adequate levels of hormone replacement; however, they all have different advantages and disadvantages. Talk to your doctor to see which approach may be right for you.

Men who have prostate cancer or breast cancer should not take testosterone replacement therapy. All men considering testosterone replacement therapy should undergo a thorough prostate cancer screening prior to starting this therapy with a rectal exam and PSA test.

In general, hormone replacement therapy is safe. Possible side effects include:

• Acne or oily skin.
• Mild fluid retention.
• Stimulation of prostate tissue, with perhaps some increased urination symptoms such as a decreased stream or frequency.
• Breast enlargement.
• Worsening of sleep apnea (a sleep disorder that results in frequent night time awakenings and daytime sleepiness).
• Decreased testicular size.

Laboratory abnormalities that can occur with hormone replacement include:

• Changes in cholesterol and lipid levels.
• Increase in red blood cell count.
• Decrease in sperm count, producing infertility (especially in younger men).
• Increase in PSA

If you are taking hormone replacement therapy, regular follow-up appointments with your doctor are important.

Like any other medication, directions for administering testosterone should be followed exactly as your doctor orders. If you are unsure or have any questions about testosterone replacement therapy, ask your doctor.