Testosterone, also known as the "male hormone", has many different functions from sex drive to muscle mass protection, from maintaining bone health to sperm production; It is a hormone produced by Leydig cells in the testicles.

Testosterone, which starts to decrease with the age of 40s, continues to decrease gradually by 1-2 percent each year with aging. This is also called andropause. In addition, genetic causes (diseases such as Klinefelter), pituitary gland diseases, tumors and surgery or radiation treatments, testicular diseases, trauma, surgery due to tumor, receiving chemotherapy, kidney failure, lung diseases, diabetes, metabolic syndrome, weight gain, obesity Chronic conditions, such as AIDS, are among the causes of low testosterone. Today, stress is among the major causes of testosterone deficiency.