What Is Low Testosterone?

Male Hypogonadism Symptoms and Causes

The straightforward, quick answer is:  testosterone is the most important male sex hormone.  It’s produced in the testes, and it’s what causes boys to go through puberty.

In men, testosterone is responsible for maintaining:

  • sex drive
  • sperm production
  • facial, pubic, and body hair
  • muscle
  • bones

The amount of testosterone in a man’s body changes throughout the day, and it’s usually highest in the morning.  A normal range of testosterone is 300 ng/dL to 1,000 ng/dL.

We have an article on the role of testosterone and the testes; read it to learn more about testosterone basics.

Low Testosterone Symptoms
If you have low testosterone levels, you may begin to notice the following signs and symptoms:

  • decreased sex drive (libido)
  • poor (or no) erections (erectile dysfunction or impotence)
  • enlarged breasts
  • low sperm count

Men with more severe cases of low testosterone may experience more severe symptoms, especially the longer their testosterone levels remain low.  Severe low testosterone may lead to signs and symptoms such as:

  • loss of body hair
  • loss of muscle bulk and strength
  • weaker bones (osteoporosis)
  • mood swings (including increased irritability)
  • depression
  • hot flashes

Low Testosterone Causes
There are several causes of low testosterone, and your doctor will work with you to figure out what’s causing your low levels.

Low testosterone is broken into 2 main types:  primary hypogonadism and secondary hypogonadism.

Primary hypogonadism is also known as primary testicular failure, and it is caused by a problem in the testicles.  These problems can include:

  • injury to the testicle:  This can be from trauma, testicular cancer, or radiation or chemotherapy to treat testicular cancer.  This trauma can affect testosterone production.
  • Klinefelter syndrome:  Males should have one X chromosome and one Y chromosomes—those are the sex chromosomes that determine gender.  In Klinefelter syndrome, there are 2 or more X chromosomes in addition to the Y chromosome, and this can lead to abnormal testicle development (and then this can affect testosterone production).
  • undescended testicles:  Sometimes, testicles do not descend prior to birth—they’re supposed to descend from the abdomen (where they develop) to the scrotum .  If the testicles don’t descend in early childhood, it could affect testosterone production.

Secondary hypogonadism is caused by a problem with the pituitary or hypothalamus glands.  Those are glands that give a signal to the testicles to make testosterone, so if something affects them, testosterone production can be affected.  Conditions that can cause secondary hypogonadism include:

  • pituitary disorders:  For example, a pituitary tumor can affect the release of hormones that tell the testes to make testosterone.  Therefore, testosterone production can be deficient.
  • medications:  Certain medications, including opioids used for severe pain, can affect testosterone production.
  • type 2 diabetes:  Having type 2 diabetes can raise your risk of developing male hypogonadism.
  • aging:  Older men have lower testosterone levels because testosterone production decreases over time.

These are just some examples of what can cause male hypogonadism.  Through the diagnosis process, which you’ll learn about in the next article, your doctor should be able to figure out why you have low testosterone levels.