Low Testosterone Health Center

There is no single cause of low testosterone. Each man may have a different reason or combination of reasons for his low testosterone. Most commonly, the cause is a combination of the following:

Normal Aging
Testosterone production naturally decreases as men age. While this reduction begins around age 40, and can decrease about 1 percent a year, most men will still remain in the "normal" range of testosterone.

Obesity
Both men and women have testosterone (the "male" hormone) and estrogen (the "female" hormone), although men have more testosterone, and women have more estrogen. Testosterone can be converted into estrogen in a normal biologic process that occurs in fat cells. When a man is obese, he has more fat, and more testosterone becomes converted into estrogen, which can leave him with a testosterone deficiency.

Testicular Injury
Damaged testicles can lead to below-normal testosterone levels. The testicles can become damaged through physical injury, chemotherapeutic injury or radiation injury (the latter two are possibilities of cancer treatment or industrial exposure). Men who have one fully functioning testicle usually can produce enough testosterone, even if the other is damaged.

Medications
Opiate painkillers such as hydrocodone, oxycodone, morphine and others can lower testosterone production over time. People who overuse testosterone (usually bodybuilders) also can have decreased testosterone production when they stop supplementing themselves (nonprescription use of anabolic steroids is illegal and they are considered a Schedule III drug, punishable by law for possessing or distributing them).

Brain Injury
Anything that disrupts the hypothalamus-pituitary axis can potentially disrupt the production of testosterone. These can be traumatic injuries or inflammatory injuries, such as:

• Sarcoidosis
• Histiocytosis
• Tuberculosis
• HIV/AIDS
• Mumps
• Meningitis
• Syphilis
• Brain tumors