Testosterone is a hormone found in humans, as well as in other animals. In men, the testicles primarily make testosterone. Women’s ovaries also make testosterone, though in much smaller amounts.
The production of testosterone starts to increase significantly during puberty and begins to dip after age 30 or so.
Testosterone is most often associated with sex drive and plays a vital role in sperm production. It also affects bone and muscle mass, the way men store fat in the body, and even red blood cell production.
A man’s testosterone levels can also affect his mood.
Low levels of testosterone, also called low T levels, can produce a variety of symptoms in men, including:
- decreased sex drive
- less energy
- weight gain
- feelings of depression
- low self-esteem
- less body hair
- thinner bones
While testosterone production naturally tapers off as a man ages, other factors can cause hormone levels to drop.
Injury to the testicles and cancer treatments such as chemotherapy or radiation can negatively affect testosterone production.
Chronic health conditions and stress can also reduce testosterone production. Some of these include:
- kidney disease
- cirrhosis of the liver
Testosterone levels decline steadily in adult women, however, low T levels can also produce a variety of symptoms, including:
- low libido
- reduced bone strength
- poor concentration
Low T levels in women can be caused by removal of the ovaries as well as diseases of the pituitary, hypothalamus, or adrenal glands.
Testosterone therapy may be prescribed for women with low T levels, however, the treatment’s effectiveness on improving sexual function or cognitive function among postmenopausal women is unclear.