Reasons for Low Testosterone

The National Institutes of Health estimate that approximately 5 million men in the United States are affected by low testosterone. In most healthy men testosterone is regulated by the body's fine-tuned systems. The hypothalamus gland triggers the pituitary gland to send a message to the testes, which then produce the right amount of testosterone. The NIH cites an expected testosterone level of 300 to 1,200 nanograms per deciliter (ng/dl). Men may experience low testosterone for a variety of reasons.

Aging

• Aging is a major reason for low testosterone. Levels of the male hormone naturally decrease over time.

Damage

• Trauma to the testicles can cause low testosterone. Accidents, cancer or chemotherapy may damage the testes.

Medications

• Medications such as morphine and steroids may affect the production of testosterone, causing low levels.

Diseases

• Some diseases, particularly genetic disorders such as Klinefelter's Syndrome, cause low testosterone.

Warning

• While a decreased interest in sex is normal as men age and testosterone levels decline, the total absence of libido is not normal. You should seek diagnosis and treatment in this situation.