Testosterone Level Information

Testosterone is a type of hormone primarily produced by men, though women also produce some testosterone. It's responsible for physical effects such as increased muscle mass, strength and bone density and the development of secondary sex characteristics.

Aging

• As men age, it's normal for them to experience a gradual decrease in testosterone levels. Abrupt changes are generally indicative of a medical problem.

Testing

• If a physician suspects an abnormal change in testosterone levels, he can order a serum testosterone test. This is a blood test that measures the amount of testosterone in the blood.

Normal Levels

• The National Institute of Health reports that the normal level of testosterone for men is 300 to 1,000 nanograms per deciliter and 20 to 80 nanograms per deciliter for women.

Conditions

• Conditions that can abnormally increase testosterone levels include testicular or ovarian cancers, androgen resistance and precocious puberty. Causes for a decrease in testosterone levels include an underactive or damaged pituitary gland, hypogonadism and illness.

Aggression

• Although blaming high testosterone levels for aggression is a common practice, a 2007 Scientific American article reports that the research doesn't support this claim. The article notes that testosterone may help to enable aggressive behavior but can't be considered the direct cause.