[Free testosterone index: comparison with plasma free testosterone].

Area of Science:

• Endocrinology
• Andrology
• Clinical Chemistry

Background:

• Free testosterone is the biologically active form, crucial for assessing androgenicity.
• Measuring free testosterone directly can be complex, necessitating reliable indirect indices.
• Sex hormone-binding globulin (SHBG) influences the levels of free testosterone.

Purpose of the Study:

• To evaluate the utility of a blood-free testosterone index in reflecting plasma free testosterone concentrations.
• To compare the blood-free testosterone index with plasma free testosterone in various physiological states and diseases.

Main Methods:

• Calculated a testosterone index by multiplying plasma testosterone concentration by the percentage of SHBG-non-bound testosterone.
• Measured blood-free testosterone indices and plasma free testosterone in normal men and women, pregnant women, and patients with hypogonadism, chronic hepatitis, liver cirrhosis, hyperthyroidism, and hirsutism.
• Correlated the testosterone index with plasma free testosterone and SHBG levels.

Main Results:

• A significant increase in plasma testosterone was observed in chronic hepatitis and hyperthyroidism compared to normal men.
• Plasma testosterone increased in pregnant and hirsute women compared to normal women.
• The blood-free testosterone index showed a close correlation with plasma free testosterone concentrations across all subjects.

Conclusions:

• The blood-free testosterone index serves as a reliable indicator of plasma free testosterone levels.
• This index is valuable for evaluating the status of androgenicity in diverse clinical scenarios.
• The study validates the blood-free testosterone index as a practical tool in endocrinological assessments.