Dihydrotestosterone in men: what is it for?

About 90% of testosterone in the blood is inactive - it is bound by a special protein that is synthesized in the liver and is called sex hormone binding globulin (SHBG), and cannot penetrate the walls of capillaries. Thus, no more than 10% of the androgen that enters the blood can actually affect the body. Part of the free testosterone in some target cells, under the influence of the enzyme 5-alpha-reductase (type 1 or 2), is converted into dihydrotestosterone, and part - into the female sex hormone estradiol (this conversion occurs under the influence of enzymes with the general name aromatase).

To be more specific, the situation is as follows: 97.3-99% of testosterone is bound by SHBG, albumin and corticosteroid binding globulin. Accordingly, 1-2.7% remains free, i.e. about 5-21 ng/dl. Testosterone is not bound tightly to albumin and can be released, usually when taking certain medications or under certain medical conditions. Such testosterone is called bioavailable, its level is approximately 12.3 to 63 percent.

After completing its mission, testosterone is destroyed and excreted from the body with urine. The process of destruction occurs in the liver. The half-life of the male sex hormone is 60-100 minutes.

As already mentioned, some of the free testosterone in some target cells is converted into dihydrotestosterone by the enzyme 5-a-reductase (type 1 or 2). Dihydrotestosterone binds to the same receptor - AR as testosterone, it also circulates in the bloodstream - the level of dihydrotestosterone in blood plasma is approximately 10% of the level of circulating testosterone. The AR-dihydrotestosterone complex is more stable (approximately three to five times) than a similar complex with testosterone. That is, the formation of dihydrotestosterone is a way to enhance the effectiveness of testosterone in target cells. This is true, but only at first glance. Firstly, studies show that with an increase in testosterone levels in the body, the lifetime of the testosterone-androgen receptor complex increases significantly and almost reaches the lifetime of the same complex with dihydrotestosterone. This is another argument in favor of high doses of testosterone. And secondly, in the human body there are two types of 5-a-reductase: type 1 is found in the skin and is the dominant enzyme in the skin of the part of the head where hair grows. Type 2 is found in the skin of the buttocks, prostate and some other tissues. From the above it follows that dihydrotestosterone is mainly responsible for the growth of the internal male genitalia, the penis during puberty (sexual maturation, to put it simply), as well as hair on the face and body. This same hormone is responsible for the occurrence of acne. At the same time, an increase in muscle mass and an increase in libido depend more on testosterone than on dihydrotestosterone - this is due to the fact that in muscle cells dihydrotestosterone is converted into "weak" androstenediol.

It turns out that all the "androgenic" troubles of testosterone come from its conversion (partial) into dihydrotestosterone?

In general, yes, but practice shows that simultaneous (with testosterone injections) use of a drug such as "Proscar" leads to a significant decrease in the effect of using the first. This is due to the fact that dihydrotestosterone has a positive effect on the central nervous system, resulting in increased strength indicators and a reduction in recovery time. So not everything "androgenic" is bad.

In addition, it turned out that dihydrotestosterone is... an anti-estrogen! Dihydrotestosterone suppresses the activity of estradiol in tissues, but not only - it also significantly reduces the rate of conversion of testosterone to estradiol by inhibiting aromatase activity. Moreover, the use of cream with dihydrotestosterone allows you to fight gynecomastia (though at stages that cannot be called advanced).

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