Testosterone testing is one of the most important indicators of men's health. Read about the proper preparation for the analysis, its interpretation and additional hormonal examinations that increase the accuracy of diagnosis.
Rules for preparing for the analysis of testosterone levels
It is important ! The laboratory may refuse to analyze in 2 cases:
- Eating any food (even tea) before the examination. Blood sampling should take place at least 8 hours after the last meal.
- Late appeal. The analysis is taken up to 11 hours in a specialized laboratory, and until 9 am in an ordinary hospital.
In all other cases, blood will be taken. Responsibility for the accuracy of the analysis lies with the patient. For the result to be correct, the following actions are not desirable:
- Ultrasound, X-ray, FLG, physiotherapeutic procedures, rectal examination the day before. It should be a day to wait.
- Medication (especially hormonal). It is necessary to cancel them and in 2 weeks to pass the test for testosterone.
- Heavy exercise, drinking alcohol, nicotine, fatty foods the day before the study.
For analysis, blood from a vein is used. Determine testosterone by ELISA (enzyme-linked immunosorbent assay). A labeled reagent is added to the taken blood, specifically binding only to this hormone (according to the key-lock principle), then staining occurs. The intensity of the color determines the amount of the desired substance. The method is accurate, errors are excluded. Unless the human factor interferes, it can distort the result.
Testosterone fractions: total, free, bioavailable
Testosterone circulating in a person’s blood has a free and bound state .
Free testosterone . The most active form of the hormone, which determines the individual male signs. Free testosterone accounts for about 2% of the total hormone content.
Associated testosterone . Such testosterone is associated with proteins. There are two forms of the hormone:
- Associated with globulin (SHBG) - about 44% of the total testosterone. This is the strongest connection, so this testosterone is inactive. It is precisely due to the association with GSPG that the proportion of free testosterone can be reduced.
- Associated with albumin - about 54% of the total testosterone. This connection is weak, it easily disintegrates, therefore such testosterone is considered active. Due to this form of the hormone, there is a rapid replenishment of free testosterone.
Free and bound to albumin testosterone is called bioavailable , with biological activity.
When to take free testosterone to a man?
If the analysis for total testosterone showed normal levels of the hormone, but there are complaints about the characteristic symptoms of androgen deficiency, then examine the fraction of free testosterone. There are 2 reasons for this situation:
- Normal levels of total testosterone can be achieved by increasing the inactive (associated with SHBG) form.
- Inconsistency in the ratio of male and female sex hormones (testosterone levels are normal, estrogen levels are elevated ).
Additional hormonal indicators
Globulin Binding Sex Hormones (SHBG)
Free testosterone is influenced by the concentration of SHBG. The link is direct: with an increase in SHBG, the level of free testosterone decreases. The increase in binding protein is caused by age-related extinction of sexual function and a number of diseases: hyperthyroidism , cirrhosis, medication, diabetes mellitus. Reveal this indicator rarely: indicators of total and free testosterone is enough. Only in cases when total testosterone is normal, and complaints are present, then SHBG is included in the indicators of hormonal levels.
Gonadotropic hormones (LH and FSH)
Two hormones of the central nervous system, produced in the brain (pituitary), stimulate the production of testosterone and affect its performance. These are luteinizing hormone (LH) and follicle-stimulating hormone (FSH) .
The decrease in the concentration of these hormones indicates a violation of the function of the pituitary or hypothalamus. A simultaneous decrease in testosterone, FSH and LH indicates a secondary hypogonadism. Normal or elevated levels of LH and FSH and low testosterone indicate primary hypogonadism.
Dihydrotestosterone is formed from free testosterone by the enzyme (5-alpha reductase). This is the most active form of testosterone (more active than free testosterone). DGT can decrease in two cases: with a lack of an enzyme or a decrease in testosterone. DHT is included in a comprehensive assessment of the hormonal status for a more accurate diagnosis.
In men, estradiol is a sex hormone that provides a counterweight to testosterone. Increasing its concentration leads to a decrease in testosterone. The examination reveals the ratio of total testosterone to etradiol. This indicator should be above 10.
Interpretation of hormone test results
A preliminary conclusion about the result of the analysis can be made by the patient himself. Testosterone levels can be measured in different values (nmol / l, ng / ml, pg / m), depending on the clinic and its test system.
Table 1 - Indicators of testosterone levels of different factions in men.
The decrease in total testosterone due to its free fraction with the characteristic symptoms of sexual failure is called hypogonadism.
Hypogonadism is primary and secondary . The primary form is found in the pathology of the genital organs, and the secondary - in the pathology of the brain.
In order to make an accurate diagnosis, you need to contact a specialist and examine the hormonal spectrum. It includes androgenic status (total, free testosterone, associated with globulin and albumin), LH, FSH, prolactin, thyroid-stimulating hormone (TSH) and estradiol. Hormonal status allows the doctor to make a more accurate diagnosis and find the necessary treatment.
High levels of sex hormones may indicate hormonal tumors (pituitary tumors, adrenal cortex). In this case, the man has a pronounced manifestation of male sexual characteristics.