The article presents indicators of the normal level of total, free and bioavailable testosterone for men, characterizes various forms of androgen, provides information on determining the level of sex hormones and other important data.

Change in testosterone levels

Testosterone levels fluctuate throughout the day (Fig. 1, graph 1). The maximum concentration of androgens is observed in the early morning, and begins to gradually decrease, reaching its minimum in the evening. Therefore, for the reliability of the analysis of sex hormones, its conduct is prescribed in the morning (up to 11 hours). In addition, the circadian rhythm of testosterone synthesis is observed, depending on the time of year (Fig. 1, graph 2).
Зависимость уровня тестостерона

Fig. 1 - Testosterone circadian and one-year rhythms:
graph 1 - testosterone circadian rhythm versus time of day;
graph 2 - testosterone circadian rhythm versus season.

The short-term fluctuation in the concentration of sex hormones is influenced by many factors: psychological state (stress, anger, depression, a sense of superiority, etc.), food intake, bad habits, physical activity. For example, after training in the gym, the level of sex hormones increases. However, the opposite situation is observed at high intensive loads, due to which the body does not have time to recover.

In general, the level of testosterone in men depends on:

  • age (by about 25-30 years, the production of sex hormone begins to decline by about 1-1.5% per year (see. Fig. 2));
  • lifestyle (a healthy lifestyle helps to improve hormonal balance, while alcohol abuse, smoking, low physical activity, unbalanced diet reduces the synthesis of sex hormones);
  • health status (immune system status, obesity, the presence of chronic diseases);
  • psychological state (the presence of stress, depression).

Динамика секреции тестостерона Fig. 2 - Age dynamics of secretion of total testosterone in men.

The rate of testosterone in men

Table 1 - Normal levels of testosterone in men

Total Testosterone, (nmol / L) 12 - 33
Biologically active testosterone, (nmol / l) 3.5 - 12
Free Testosterone, (pg / ml) 4.5 - 42

Calculator for calculating free and biologically active testosterone

The overall normal rate for males is 12–33 nmol / l (345–950 ng / dl). These are indicators that a man should “fit into” during his lifetime, without taking into account the age category. If we take into account age differences, it turns out that in young men under 25 the desired minimum starts from the average norm, and men over 50 need to maintain a level not below the critical point.

Testosterone Forms (Fractions)

There are three forms of testosterone:

  • Associated with GPSS - inactive form (about 57%);
  • Albumin-associated - active (bioavailable) form (about 40%);
  • Free testosterone - has maximum bioavailability (1-3%).
Total Testosterone =   T associated with SHGP + T associated with albumin + T free.

Thus, the level of total testosterone indicates a quantitative indicator of all forms of T in the blood, and in some cases can not be used as a defining indicator of the degree of androgen deficiency, because the level of total testosterone can remain normal, while T of an inactive form will prevail over its bioavailable fraction.

Bioavailable testosterone = T associated with albumin + T free.

It is bioavailable forms of T have an effect on the body, because able to penetrate androgen-sensitive cells, which can not T associated with GPSS, due to their strong connection.

How to determine the level of testosterone?

A blood test provides an accurate numerical representation of the level of sex hormones in the blood. But even here there are pitfalls: in medicine there is no standardized method for determining the level of androgens , and, often, the result of the analysis will depend on the method used. It is recommended to do the analysis several times in different clinics, to obtain an approximate average value. The point of repeated analyzes is that the concentration of hormones may vary on different days.

Analysis of the testosterone level is best to pass in the morning. Before analysis is not recommended:

  • there is (8 hours before the analysis);
  • engage in sports and heavy physical activity (at least 24 hours before the analysis);
  • smoke (4 hours before analysis).

Non-compliance with the recommendations will affect the accuracy of the analysis.

How to determine the level of testosterone in men by external signs?

In men, a prolonged decline in androgens in the blood can manifest itself, as shown in Figure 3.

Определение уровня тестостерона у мужчин

Fig. 3 - Signs of low testosterone levels in men.

When detecting 3 or more signs at the same time, it is necessary to pass a blood test for sex hormones.

An insufficient number of androgens in men is not only an age-related problem (see age-related androgenic deficiency ). Androgen deficiency is increasingly common among young men whose age does not exceed 25 years. According to medical data, the level of testosterone in men over the past 50 years has decreased by 1.5-2 times. This suggests that the androgen deficiency ceases to be predominantly an age prerogative, and is a consequence of changes in the lifestyle of the individual.

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