Testosterone is a sex hormone that plays a very important role in the body.  In men, it is thought to regulate (or affect) libido (sex drive), bone density, fat distribution, mental acuity, muscle mass, strength, and the production of red blood cells and sperm.  Low testosterone can negatively affect all of these areas.  Testosterone is primarily produced in the testes, though some is produced in the adrenal glands.  The amount of testosterone produced is regulated by the hypothalamus and the pituitary gland.  The medical term for low testosterone is Hypogonadism, commonly referred to as “Low T.”

Optimal Testosterone Level

In men, testosterone levels typically range between 300-1000 nanograms per deciliter (ng/dl).  These levels are controlled by regulatory hormones produced in the brain, which increase when testosterone levels are low and decrease when levels are high, but as men age, testosterone levels tend to gradually decrease, so whether or not a man exhibits symptoms of low testosterone is a critical factor in determining whether his testosterone levels need to be increased.

Older man pinching his nose

Symptoms of Low Testosterone

  • Decreased sex drive
    Testosterone plays a key role in a man’s libido (sex drive).
  • Difficulty with erections
    Testosterone aids in achieving and maintaining an erection.
  • Decreased sperm production
    Testosterone is vital to sperm production.
  • Decreased muscle mass
    Testosterone plays a role in building muscle.
  • Increased body fat
    Testosterone deficiencies can cause an increase in body fat due to an imbalance between hormones.
  • Decreased energy
    Testosterone plays a key role in overall energy, which can affect work performance.
  • Depression
    Testosterone deficiencies can cause men to be depressed, irritable, and lacking in focus, which can affect interpersonal relationships.
  • Decreased bone mass
    Testosterone helps maintain bone strength and density.
  • Hair loss
    Testosterone plays a role in several body functions, including hair production.

Causes of Low Testosterone

On average, a man 30+ years old loses about one percent (1%) testosterone per year for the rest of his life, simply from aging.  Low testosterone can also be caused by an injury to the testes or by a defect in the testes which is known as Primary Hypogonadism, a signaling problem between the brain and testes causing the production of testosterone to drop too low.  If the brain believes there is too much testosterone in the body, it may signal the testes to reduce production, this is known as Secondary Hypogonadism.

Man paragliding

Possible Causes of Primary Hypogonadism

  • Undescended or absent testes
  • Injury resulting in loss of testes
  • Inflammation of the testes
  • Surgical removal of testes
  • Genetic abnormalities, such as Klinefelter Syndrome, in which males have an extra "X" chromosome
  • Chemotherapy that causes loss of normal testicular function
  • Damage to testes from alcohol or heavy metals

Possible Causes of Secondary Hypogonadism

  • Genetic abnormalities resulting in an abnormal function of the hormones from the brain and pituitary gland controlling the testes

  • Tumor, trauma, or radiation involving the pituitary gland's control of the testes