7 Causes of Low Testosterone

by Chris Regal Editor

Testosterone is the predominant male sex hormone produced by the body. As a man ages, testosterone levels will decrease naturally; however, a steep decrease in testosterone could be the product of a more serious condition. If symptoms seem out of the ordinary, consider consulting a doctor.


As men age, testosterone levels naturally go down. This process is sometimes referred to as the "male menopause" or andropause. This process occurs when the amount of testosterone in the body decreases and production slows. Most men lose 30 to 40 percent of testosterone between ages 48 and 70. This process can lead to loss of muscle strength, increase in body fat and decreased sexual drive or functionality.


Not all cases of low testosterone are a product of the body naturally malfunctioning. An injury to the testes, which produces the hormone, can also cause low testosterone. If a man is experiencing the symptoms of low testosterone – low sex drive, fatigue, muscle loss, depression– he should consider being checked for an injury to his testes.

Hormone therapy

When a man has prostate cancer, the cancer feeds on male hormones, including testosterone. One of the goals of hormone therapy is to deprive the cancer of fuel by dramatically decreasing the amount of male hormones in the body, including testosterone. Hormone therapy is often used for those men who cannot have surgery or have a type of cancer that has returned after other means of treatment.


Male hypogonadism is characterized by the failure to produce testosterone or a decrease in the production of testosterone. This occurs when the testes fail to function normally because of a genetic defect, illness or injury or because of the failures of another hormonal gland. Whereas testosterone inhibits the growth of muscle and body hair, men with hypogonadism may experience late puberty (or not at all).


Obesity can cause a myriad of problems for men, including increased risk of heart disease, stroke, and diabetes. Another effect of obesity is a change in hormonal levels in the body. Testosterone helps build muscle in men and when testosterone levels decrease, muscle mass decreases and fat deposits begin to accumulate. Low testosterone levels in men can also lead to decreased sexual drive, low sperm count and problems with erections.

Chemo/radiation treatment

If a man is undergoing chemotherapy or radiation, low testosterone is not an uncommon side effect. In some cases, chemotherapy can damage the testes and can affect the levels of testosterone produced by the glands, leaving a man with a decreased amount of the hormone. Often, a man with low testosterone as a product of one of these treatments will also be given a prescription for testosterone supplementation.

Infectious disease

The testes can be affected by some infectious diseases, including mumps. If a man catches the disease early in his life, it could cause long-term problems for the production of testosterone. Other infectious diseases that can impair testosterone production include tuberculosis and HIV.

Chris Regal
Meet Our Writer
Chris Regal

Christopher Regal is a former Web Producer for a variety of conditions on HealthCentral.com, including osteoarthritis, chronic pain, multiple sclerosis, ADHD, Migraine, and prostate health. He edited, wrote, and managed writers for the website. He joined HealthCentral in November 2009 after time spent working for a political news organization. Chris is a graduate of the Catholic University of America and is a native of Albany, New York.