Testosterone is a hormone present in men and, in smaller quantities, in women that circulates in the blood bound to proteins, such as albumin or globulin, or free to perform its function in the body.
Testosterone dosage may be indicated when a person presents symptoms that may indicate changes in the levels of this hormone in the body, such as difficulty gaining muscle mass, excess facial hair or difficulty getting pregnant.
Read too: Testosterone: what it is, what it is for, symptoms and how to increase it
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In case of changes in the result of the total or free testosterone test, it is recommended to consult an endocrinologist who, normally, takes into account the person’s health status and the results of other tests when interpreting them.
What is it for
The free and total testosterone test is used to assess testosterone levels in both men and women, being useful for investigating the causes of erectile dysfunction, decreased libido and menstrual irregularities, for example.
The types of testosterone that can be measured in the exam are:
- Testosterona total, which is the total amount of testosterone produced in the body and which is circulating associated with proteins;
- Free testosterone, which corresponds to 2 to 3% of total testosterone and is not bound to proteins, being absorbed and exerting its activity in the body.
Normally, the doctor indicates the dosage of both free and total testosterone to better assess the person’s health status.
When the exam is indicated
The total and free testosterone test may be recommended by the doctor in the following situations:
- Decreased libido;
- Difficulty getting pregnant;
- Erectile dysfunction;
- Suspected changes in the adrenal or pituitary glands;
- Changes in the menstrual cycle;
- Investigation of Polycystic Ovary Syndrome;
- Investigation of ovarian tumor or changes in the testicle;
- Suspected precocious puberty or pubertal delay.
The total and free testosterone test is normally indicated along with other tests, such as a blood count and measurement of other hormones, as this makes it possible to make a more accurate diagnosis and thus initiate the most appropriate treatment.
Reference values
Reference values may vary according to the laboratory in which the test is performed, as different methods may be used, and may vary according to age.
Don’t ignore your symptoms!
In general, normal values of testosterona total in the blood are:
- Men between 22 and 49 years old: 241 – 827 ng/dL;
- Men over 50: 86,49 – 788,22 ng/dL;
- Women between 16 and 21 years old: 17.55 – 50.41 ng/dL;
- Women over 21: 12.09 – 59.46 ng/dL;
- Menopausal women: up to 48.93 ng/dL.
It is important that the total testosterone result is evaluated by the doctor taking into account the free testosterone result and other hormonal tests that may have been requested.
Free testosterone reference value
The following table indicates the reference value for free testosterone in the blood according to the man’s age, and the result may also vary according to the laboratory:
The following table indicates the reference value for free testosterone in the blood according to the woman’s age and menstrual cycle phase, and the result may also vary according to the laboratory:
What does the result mean
The result of the free and total testosterone test must be analyzed by the doctor, and it is important to take into account the person’s age, the phase of the menstrual cycle, in the case of women, the practice of physical activity and the presence of any chronic disease.
Low total and free testosterone
Testosterone may be reduced in cases of hypogonadism, testicular removal, Klinefelter syndrome, uremia, hemodialysis, liver failure, excessive alcohol consumption by men and use of medications such as digoxin, spironolactone and acarbose.
Furthermore, injuries to the testicles due to trauma, infection or alcohol abuse, for example, or late puberty can also promote a decrease in testosterone levels.
Read too: Low testosterone: what it is, symptoms, causes, tests and treatment
High total and free testosterone
Testosterone may be increased in cases of precocious puberty, adrenal hyperplasia, ovarian or testicular cancer, hyperthyroidism, hormone replacement with testosterone or use of anabolic steroids, for example.
Read too: High testosterone: what it is, symptoms, causes and treatment
Bibliography
- UNIVERSITY OF ROCHESTER MEDICAL CENTER. Total Testosterone. Available at: <https://www.urmc.rochester.edu/encyclopedia/content.aspx?contenttypeid=167&contentid=testosterone_total>. Accessed on February 27, 2024
- LOGAN HEALTH. Testosterone, Total and Free, Serum. Available at: <https://logan.testcatalog.org/show/TES-FR>. Accessed on February 27, 2024
- STATPEARLS. Physiology, Testosterone. 2023. Available at: <https://www.ncbi.nlm.nih.gov/books/NBK526128/>. Accessed on February 27, 2024
- KEEVIL, Brian G; ADAWAY, Jo. Assessment of free testosterone concentration. J Steroid Biochem Mol Biol. Vol.190. 207-211, 2019
- MEDLINEPLUS. Testosterone Levels Test. Available at: <https://medlineplus.gov/lab-tests/testosterone-levels-test/>. Accessed on February 27, 2024
