What Causes Decreased Testosterone in Men?

Decreased testosterone in men may be a natural occurrence or the result of medical problems. Testosterone levels naturally decline as a man ages, escalating after the age of 50. Medical conditions related to low testosterone levels include testicular infections, cancer, and chronic kidney failure.

The aging process is a natural cause of decreased testosterone in men. Levels of the hormone begin to decline around the age of 30 and continue to decrease throughout a man’s life. After age 50 testosterone levels decline rapidly, and although low testosterone levels are common in older men, relatively few receive treatment for the problem.

One of the most basic causes of decreased testosterone in men is injury, infection, or loss of testicles. The source for the majority of male testosterone is the testicles, and significant injuries can cause the organs to produce insufficient amounts of the hormone. An absence of testicles and testicular infections caused by bacteria or illnesses, such as mumps, also may prevent the production of an adequate amount of testosterone.

Cancer treatments are another major cause of low testosterone. Both radiation and chemotherapy can result in decreased testosterone in men. Some medications and treatments used to treat specific kinds of cancer may have similar effects, including hormone treatments used to treat prostate cancer. Corticosteroid, a steroid used to treat brain tumors and many other ailments, may lower testosterone as well.

In some cases, the cancer itself causes the problem. The pituitary gland produces hormones that control the function of a number of organs, including the testicles, and pituitary tumors can lead to the gland’s dysfunction. Faulty signals sent from the pituitary gland to the testicles often result in low levels of testosterone.

Other medical conditions also can cause testosterone deficiency in men. Hemochromatosis causes the body to absorb and retain too much iron, and the late stages of the disease have been associated with testicular atrophy. Inflammatory diseases, kidney failure, and chronic illnesses may lower testosterone levels as well.

Genetic abnormalities and birth defects may also cause decreased testosterone in men. Cryptorchidism is the failure of one or both testicles to descend into the scrotum before birth, and if they do not descend either naturally or through surgery, testosterone production can decrease. Even if corrective surgery takes place in the first months of life, some patients may experience issues with testosterone production and infertility in adulthood. Klinefelter’s Syndrome is a genetic abnormality in which men have an extra X chromosome. One symptom of the syndrome is the development of small testicles, which could cause low testosterone levels.