What is low testosterone (male hypogonadism)?

Low testosterone (male hypogonadism) is a condition in which the testes (testicles, the male reproductive glands) do not produce enough testosterone (a male sex hormone).

In men, testosterone helps maintain and develop:

  • Sexual features
  • Muscle mass
  • Adequate levels of red blood cells
  • Bone density
  • Sense of well-being
  • Sexual and reproductive function

How common is low testosterone?

Low testosterone affects almost 40% of men aged 45 and older. It is difficult to define normal testosterone levels, because levels vary throughout the day and are affected by body mass index (BMI), nutrition, alcohol consumption, certain medications, age and illness.

What causes low testosterone?

As a man ages, the amount of testosterone in his body gradually drops. This natural decline starts after age 30 and continues (about 1% per year) throughout his life.

There are many other potential causes of low testosterone, including the following:

What are the symptoms of low testosterone?

Symptoms of low testosterone depend on the age of person, and include the following:

  • Low sex drive
  • Erectile dysfunction
  • Decreased sense of well-being
  • Depressed mood
  • Difficulties with concentration and memory
  • Fatigue
  • Moodiness and irritability
  • Loss of muscular strength

Other changes that occur with low testosterone include:

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