Free testosterone index

Why this test?

To identify the causes of early puberty or delayed sexual development in boys.

To identify the causes of impotence and infertility in men.

For the diagnosis of testosterone-producing tumors of the gonads.

To detect polycystic ovaries and other causes of virilization in women.

To monitor the treatment of prostate cancer with gonadoliberin analogues and antiandrogens.

To identify the causes of acne.

For the diagnosis of hypothalamic-pituitary disorders, assessment of the function of the body's endocrine system.

To clarify the gender of newborns with ambiguous sexual characteristics.

In what cases is it prescribed?

For both sexes in case of an androgens level increase or decrease with a normal level of testosterone; alopecia; acne rash; oily seborrhea; detection of markers of insulin resistance.

For women, it is prescribed in case of hirsutism; anovulation; amenorrhea; polycystic ovary syndrome.

For men, it is prescribed in case of menopause; chronic prostatitis; Violation of potency; decrease in libido.

Testing preparation 

Do not eat for 12 hours before the testing.

Exclude taking estrogen, androgen 48 hours before the testing.

In the absence of special instructions from the doctor, it is recommended to give blood for analysis before 11 o'clock in the morning.

Exclude physical and emotional overstrain 30 minutes before the testing.

Do not smoke for 30 minutes before the testing.

Test information

The free testosterone index is a calculated indicator that determines the ratio of the molar concentration of total testosterone to the molar concentration of globulin-binding sex hormones (GBSH), expressed in %. This indicator correlates with the content of biologically available testosterone and is used as an informative marker of androgenic status.

In order for testosterone to be delivered to the target cells, transport proteins-globulins (GBSH) are necessary. Their task is also to correct the level of testosterone, since the testosterone associated with them is not active. This protein is produced in the liver. The amount of active testosterone that can perform its functions normally depends on age and GBSH concentration. Total testosterone includes both free and bound fractions. Therefore, its level may be within the normal range, but at the same time, disorders of sexual functions will be observed, since the concentration of the active hormone will be low.