Where is Testosterone Produced?

In both sexes, the body produces testosterone in the gonads, the Leydig cells in men’s testes, and the ovaries in women. The pituitary gland and the hypothalamus regulate testosterone levels, with the latter producing higher amounts in the morning and lower levels later in the day. The pituitary gland releases luteinising hormone in response to a hormone called gonadotrophin-releasing hormone (GnRH). This luteinising factor flows through the bloodstream to the gonads and activates the production of testosterone.

In both sexes, testosterone levels peak during puberty and gradually decrease through the early to mid-20s. In men, it is thought that testosterone regulates mood, and may perform other functions as well. It is also thought to be responsible for the production of certain chemicals, including estrogen. However, many of these functions remain unknown. The testes produce testosterone, while the brain controls its production through a ‘feedback loop’.

While males produce the most testosterone, women synthesize it in smaller amounts. In women, the adrenal glands and the thecal cells of the ovaries produce testosterone in smaller amounts. The testes contain Sertoli cells that are required for spermatogenesis, and produce most of the hormone. Testosterone is transported through the blood, bound to sex hormone-binding globulins.

Physiologically, testosterone is produced from weak androgen precursors by enzymes in the adrenal cortex. The adrenal cortex secretes androstenedione into the bloodstream, where it is converted to testosterone. While production of testosterone declines with age, it continues throughout the post-menopausal stage. The liver has the ability to create active androgens from circulating precursors. This process is known as steroid synthesis.