1. Low Testosterone Pictures Slideshow
2. Take the Low Testosterone (Low T) Quiz
3. Impotence Pictures Slideshow

Medical Author:

Benjamin Wedro, MD, FACEP, FAAEM

Benjamin Wedro, MD, FACEP, FAAEM

Dr. Ben Wedro practices emergency medicine at Gundersen Clinic, a regional trauma center in La Crosse, Wisconsin. His background includes undergraduate and medical studies at the University of Alberta, a Family Practice internship at Queen's University in Kingston, Ontario and residency training in Emergency Medicine at the University of Oklahoma Health Sciences Center.

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Medical Editor:

Ruchi Mathur, MD, FRCP(C)

Ruchi Mathur, MD, FRCP(C)

Ruchi Mathur, MD, FRCP(C) is an Attending Physician with the Division of Endocrinology, Diabetes and Metabolism and Associate Director of Clinical Research, Recruitment and Phenotyping with the Center for Androgen Related Disorders, Department of Obstetrics and Gynecology at Cedars-Sinai Medical Center.

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In this Article

• Low testosterone facts
• What is testosterone?
• What is low testosterone?
• What are the causes of low testosterone?
• What are the symptoms of low testosterone?
• When should I seek medical care for low testosterone?
• How is low testosterone diagnosed?
• What is the treatment for low testosterone?
• What are the complications of low testosterone?
• Can low testosterone be prevented?
• What is the outlook for a patient with low testosterone?
• Low Testosterone (Low T) - Slideshow
• Take the Low Testosterone (Low T) Quiz
• Erectile Dysfunction (Impotence) - Slideshow
• Low Testosterone (Low T) FAQs
• Patient Comments: Low Testosterone (Low T) - Symptoms
• Patient Comments: Low Testosterone (Low T) - Causes
• Find a local Endocrinologist in your town
• Low Testosterone Index

Low testosterone levels may be caused by a number of factors. For example – there may be a problem at the level of the hypothalamus or pituitary to produce appropriate amounts of LH and FSH to stimulate testosterone production. Another possibility is that the organs that make testosterone do not function normally or are not able to respond to stimulation by the brain. Also, as mentioned, changes in SHBG can affect for the amount of testosterone that is available to exert its effects.

• When the problem is in the organs that produce testosterone (the ovaries or testes, for the most part), it is called a "primary" problem". In medical terminology, the decrease in normal testosterone production is called "hypogonadism."
• When the problem is related to the pituitary and its ability to regulate testosterone, it is called "secondary hypogonadism," and
• If the problem is thought to be at the level of the hypothalamus, it is called "tertiary hypogonadism."

Some common causes of primary hypogonadism or failure of the gonads (the medical term for the sex organs, or testes and ovaries) may include the following:

• Undescended testicles: If the testes fail to migrate from inside the abdomen into the scrotum during fetal development or in the first year or two of life, the testes may become damaged and unable to produce adequate amounts of testosterone.
• Injury to the scrotum: If the testes are injured, they may not be able to produce adequate testosterone. Damage to one testicle does not often to lead to low levels if the other testis remains normal.
• Cancer therapy: Chemotherapy and radiation therapy can damage the interstitial cells in the testes responsible for testosterone production. This decrease in testosterone production may be temporary as the cells recover, or it may be permanent.
• Aging: Testosterone levels gradually decrease with aging. Usually, enough testosterone is manufactured to allow for adequate bodily functions, but there is some research that suggests that lower testosterone levels can result in a variety of medical problems such as bone and muscle loss, and erectile dysfunction.
• Mumps orchitis: The mumps virus can cause inflammation of the testes in males, and if the illness occurs in puberty or adulthood, the damage to the testes may lead to low testosterone production. Immunization against the mumps has significantly decreased the incidence of this illness.
• Chromosomal abnormalities: A normal male has one X and one Y chromosome (a normal female has two X chromosomes). In Klinefelter's syndrome, in males, an extra X chromosome is present and among other anatomic issues, there is abnormal development of the testes and decreased ability to manufacture testosterone.
• Ovary conditions in women: Premature ovarian failure and surgical removal of both ovaries (bilateral oophorectomy) are conditions associated with lower circulating testosterone levels.

Secondary and tertiary hypogonadism may be due to damage of the hypothalamus or pituitary and/or the failure of the production of hormones (GRH, TSH and/or LH) to stimulate the gonads.

Causes of secondary and tertiary hypogonadism include:

• Damage to the pituitary gland may occur because of tumors of the gland itself or because of damage caused by the side effects of treatment of nearby brain tumors.
• Hypothalamus malformations can prevent normal function. Kallman's syndrome is one example.
• Decreased blood flow to these glands from other conditions including significant bleeding and shock.
• Inflammation caused by tuberculosis and sarcoidosis may affect the pituitary gland.
• HIV and AIDS may also cause inflammation of both the hypothalamus and pituitary.
• Illegal use of anabolic steroids, for example in athletes and body builders, can cause hypogonadism and low testosterone levels.

It should be noted that obesity also can be a cause of low testosterone. While it can be associated with other causes, obesity specifically enhances the conversion of testosterone to estrogen. This is a naturally occurring process in both men and women, and this conversion occurs predominantly in fat cells. In the case of obesity, the large amount of fat cells enhances this process, and testosterone levels may fall due to excessive conversion to estrogen.

There are rarer causes of hypogonadism that can occur, dealing with cellular mechanisms and receptor binding. These are beyond the scope of this discussion.