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Testosterone in men: what is it for?
Last reviewed: 04.07.2025

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Testosterone is a male sex hormone produced in the testicles of men. To be more specific, it is produced by the so-called Leydig cells, a collection of these cells is also called the pubertal gland. In addition to the testicles, testosterone is also synthesized from androstenedione, produced by the reticular zone of the adrenal cortex. Every day, the male body synthesizes about 6-7 milligrams of the hormone, its level in the blood fluctuates from 300 to 1000 nanograms per deciliter. Oddly enough, but men do not have the exclusive right to produce the male sex hormone - testosterone is also produced in the female body (in the same adrenal cortex and ovaries), however, in much smaller quantities - only 1 milligram per day. Testosterone is synthesized from cholesterol, there are two options for its synthesis, the first and second, which do not differ so significantly.
In any case, a substance called a testosterone precursor or prohormone is converted directly into testosterone. Testosterone synthesis occurs, as already mentioned, mainly in the testicles (Leydig cells). Mainly under the influence of the pituitary luteinizing hormone (LH or lutropin). LH, in turn, is produced in the pituitary gland under the influence of a hypothalamic hormone called gonadotropin-releasing hormone (GnRH, GtRH). The pituitary gland uses information about the presence of sex hormones in the blood to regulate the production of LH, and the hypothalamus - to regulate the production of GnRH. In any case, an increase in the level of free testosterone in the body is a signal for the pituitary gland to reduce the production of LH, and since the production of luteinizing hormone decreases, the production of its own testosterone also decreases.
The role of testosterone in the body of men and women
The importance of the testosterone hormone for men is hard to overestimate; testosterone is what makes us men - it is responsible for the formation of secondary sexual characteristics. It is thanks to it that men have the good fortune to have lush facial and body hair; it is thanks to it that we have a lower voice and a more aggressive character than the fair sex. Finally, it is testosterone that can contribute to baldness in men, not all, of course, but some. Testosterone also activates anabolic processes in the body - it is this property that was taken as the basis for the use of this hormone both in medical practice and in sports.
Testosterone is also an important hormone for women. The first to be noticed was the connection between the level of testosterone in women's blood and fat deposition. In the period preceding menopause, as well as after it, the level of testosterone in the body of women decreases significantly. It is during this period that women are most prone to fat deposition. However, testosterone was used as an auxiliary means for getting rid of excess fat under the skin and for patients who saw the onset of menopause only in the very distant future, but the level of this hormone in the blood was clearly below normal.
In addition, a lack of testosterone in the blood of women can significantly weaken sexual desire; low testosterone levels contribute to problems with concentration, and increase the likelihood of depressive states. Moreover, a lack of testosterone leads to increased dryness and thinning of the skin. So, the importance of this hormone for women is no less difficult to overestimate than for men.
Testosterone levels in a man's body
The level of testosterone in the blood of men increases very strongly during puberty, their own testosterone in adolescence may be quite enough to form an athletic physique. But after 45-50 years, the level of testosterone in the male body begins to steadily and quite sharply decrease, and the level of estrogen increases. Taken together, these two factors inevitably lead to various and very unpleasant disorders, among which are problems with the prostate, cardiovascular system, memory, diseases associated with weakened immunity and even age-related gynecomastia (enlargement of the mammary glands). By the way, recent studies show that it is not the total level of testosterone that decreases in old men, but the level of free testosterone. This is due to an increase in the level of globulin in their blood that binds sex hormones. Be that as it may, during this period, additional injections of testosterone are very, very desirable. And not only testosterone injections - insulin helps to fight the increased level of SHBG in the blood. The testosterone level has daily fluctuations: the maximum is at 7-9 am, the minimum at 0-3 am. One interesting observation is connected with such fluctuations: even a fairly large amount of a short-lived steroid (up to 100 mg of methandrostenolone) introduced into the body during the maximum period (6 am - 12 pm) practically does not disrupt the production of endogenous testosterone. The statement, by the way, is not groundless - it is confirmed by practice.
In addition to daily fluctuations, testosterone in men's blood also has seasonal fluctuations: it increases in spring, and its peak occurs at night. Beginning in July, testosterone levels gradually decrease, and reach their lowest value by mid-September. This is the time most "favorable" for the onset of autumn depression.