Low Testosterone (Low-T) Causes

What Causes Low Testosterone (Low-T)?

Testosterone is a steroid hormone made by the testes in men. In women, the ovaries produce a small amount of testosterone. Testosterone is responsible for developing and maintaining male sex organs and secondary sex characteristics like hair growth patterns and deepening of the voice. It also augments muscle and bone growth. Testosterone is also necessary for sexual function and libido. Testosterone is regulated by hormones from the hypothalamus of the brain and from the pituitary gland.

Damage to the sex organs

In men, as you age, testosterone levels gradually decrease. Low levels of testosterone (Low-T) can also occur due to a problem with a man's sex organs (known as primary hypogonadism), the pituitary gland (secondary hypogonadism), or the hypothalamus (tertiary hypogonadism). As a male, types of conditions that can be associated with damage to your sex organs and can cause low T include:

  • inflammation of your testes (orchitis),
  • cancer therapy,
  • undescended testicles,
  • injury to your scrotum,
  • chromosomal problems, and
  • medications.

Damage to the pituitary or hypothalamus

Damage to the pituitary gland or hypothalamus of the brain can also cause low T by decreasing levels of the hormones that control your testosterone production. Types of conditions that can damage your pituitary and hypothalamus include:

  • tumors,
  • shock,
  • structural abnormalities, and
  • other causes of inflammation of these structures such as tuberculosis.

Obesity and other causes

If you are obese, this can be another potential cause of low T. Because fat cells convert androgens (male hormones) to estrogen in both men and women, the excess of fat cells in obesity can result in low T due to its conversion to estrogen. The illegal use of anabolic steroids (such as by bodybuilders and athletes) has also been shown to cause low T.

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Medically reviewed by Michael Wolff, MD; American Board of Urology


MedscapeReference.com. Low Testosterone.