A Closer Look at Testosterone Deficiency

Testosterone deficiency, also known as hypogonadism, is acondition in which the testes are unable to produce enoughtestosterone to fulfill the body's needs. Testosteronedeficiency has many possible causes, including geneticabnormalities, injury to the testes, and being on certainmedications. Normal aging also may play a role in the decline ofmale testosterone levels. It is also known as low testosterone.The testes produce testosterone regulated by a complex chain ofsignals that begins in the brain. This chain is called thehypothalamic-pituitary-gonadal axis. The hypothalamus secretesgonadotropin-releasing hormone (GnRH) to the pituitary gland inspurts, which trigger the secretion of leutenizing hormone (LH)from the pituitary gland. This hormone stimulates the Leydigcells of the testes to produce testosterone. Normally, thetestes produce 4-7 milligrams (mg) of testosterone each andevery day.After puberty, testosterone production increases rapidly, andwill decrease rapidly after age 50. Recent estimates show thatapproximately 13 million men in the United States experiencetestosterone deficiency and less than 10-percent receivetreatment for the condition, which is growing in culturalacceptability.Studies also have shown that some men with obesity, diabetes, orhypertension may be twice as likely to have low testosteronelevels, though as stated, low testosterone and testosteronedeficiency can be caused by taking certain medications,chemotherapy, infections and other basic causes.Signs of testosterone deficiency depend on the age of onset andthe duration of hormonal deficiency. Congenital testosteronedeficiency is usually characterized by underdeveloped genitalia,and sometimes even undeterminable genitalia. Acquiredtestosterone deficiency that develops near puberty can result inenlargement of breast tissue (gynecomastia), sparse or absentpubic and body hair, and underdeveloped penis, testes, andmuscle. Adults may experience diminished libido, erectiledysfunction, muscle weakness, hair loss, depression, and othercommon mood disorders.