A Closer Look at Testosterone Deficiency
Testosterone deficiency, also known as hypogonadism, is a
condition in which the testes are unable to produce enough
testosterone to fulfill the body's needs. Testosterone
deficiency has many possible causes, including genetic
abnormalities, injury to the testes, and being on certain
medications. Normal aging also may play a role in the decline of
male testosterone levels. It is also known as low testosterone.
The testes produce testosterone regulated by a complex chain of
signals that begins in the brain. This chain is called the
hypothalamic-pituitary-gonadal axis. The hypothalamus secretes
gonadotropin-releasing hormone (GnRH) to the pituitary gland in
spurts, which trigger the secretion of leutenizing hormone (LH)
from the pituitary gland. This hormone stimulates the Leydig
cells of the testes to produce testosterone. Normally, the
testes produce 4-7 milligrams (mg) of testosterone each and
every day.
After puberty, testosterone production increases rapidly, and
will decrease rapidly after age 50. Recent estimates show that
approximately 13 million men in the United States experience
testosterone deficiency and less than 10-percent receive
treatment for the condition, which is growing in cultural
acceptability.
Studies also have shown that some men with obesity, diabetes, or
hypertension may be twice as likely to have low testosterone
levels, though as stated, low testosterone and testosterone
deficiency can be caused by taking certain medications,
chemotherapy, infections and other basic causes.
Signs of testosterone deficiency depend on the age of onset and
the duration of hormonal deficiency. Congenital testosterone
deficiency is usually characterized by underdeveloped genitalia,
and sometimes even undeterminable genitalia. Acquired
testosterone deficiency that develops near puberty can result in
enlargement of breast tissue (gynecomastia), sparse or absent
pubic and body hair, and underdeveloped penis, testes, and
muscle. Adults may experience diminished libido, erectile
dysfunction, muscle weakness, hair loss, depression, and other
common mood disorders.