Free Androgen Index (FAI)
Understanding Free Androgen Index (FAI)
What is Free Androgen Index (FAI)?
The Free Androgen Index (FAI) is a blood test that measures the ratio of testosterone to sex hormone binding globulin (SHBG). It is used to assess abnormal androgen levels and diagnose hormonal disorders.
The Free Androgen Index (FAI) (FAI) test helps evaluate androgen hormone levels in the body. Androgens, such as testosterone plays an important role in male and female reproductive health influencing libido, fertility, secondary sexual characteristics (hair growth, muscle mass, voice hoarseness etc.), menstrual cycles and ovarian function.
This test measures testosterone in the blood and compares the total amount of testosterone to SHBG in the body. It is recommended as a baseline investigation for suspected hyperandrogenism (androgen excess) in women. Also, it is done when there are signs and symptoms of abnormal androgen levels, which differ in men and women.
No special preparation is required for this test. Inform your doctor about all the medications or supplements that you may be taking as these may affect the test results potentially requiring adjustments or temporary discontinuation. Also, inform your doctor if you're pregnant as it can influence the testosterone levels as part of normal physiology. Moreover, narrate your complete medical history to the doctor to help them correlate your clinical and laboratory findings.
Lab Test results may vary based on the age, gender and overall health. The interpretation of test results requires professional expertise. Do not self-medicate at home and consult the doctor to understand the test results correctly.
What is Free Androgen Index (FAI) used for?
The Free Androgen Index (FAI) test is done to:
- Assess androgen levels in individuals presenting with symptoms of hormonal imbalance.
- Evaluate conditions like Polycystic ovary syndrome (PCOS) in women, which can affect fertility and menstrual regularity.
- Investigate low testosterone levels in men, contributing to issues like erectile dysfunction and decreased libido.
- Monitor hormone levels in individuals undergoing treatments for hormonal disorders.
- Aid in diagnosing conditions related to androgen excess or deficiency, guiding appropriate management strategies.
- To monitor the effectiveness of any ongoing treatment such as hormonal replacement therapy or medications to regulate androgen levels.
What does Free Androgen Index (FAI) measure?
Contains 3 testsThe Free Androgen Index (FAI) test measures several key components to assess androgen status in the body. It evaluates total testosterone, which reflects the overall amount of testosterone present in the blood, including both free and bound forms. It measures Sex Hormone Binding Globulin (SHBG), a protein that binds to testosterone and regulates its bioavailability. Additionally, it also measures Free Androgen Index, a calculated ratio derived from the levels of total testosterone and SHBG, indicating the amount of free testosterone available for biological activity. The Free Androgen Index (FAI) is a useful clinical tool for evaluating androgen status in women, particularly in diagnosing conditions like polycystic ovary syndrome (PCOS) and hirsutism, by providing insight into the balance between total testosterone and sex hormone-binding globulin (SHBG). In men, the Free Androgen Index (FAI) is useful for assessing androgen levels, particularly in diagnosing conditions like hypogonadism and monitoring testosterone therapy.
Understanding these measurements is crucial for diagnosing and treating hormonal disorders, ultimately enhancing quality of life and reproductive function.
Sex Hormone Binding Globulin
The Sex Hormone Binding Globulin test measures the level of sex hormone binding globulin (SHBG) protein in the blood and is most often used to help evaluate you for testosterone deficiency or excess. SHBG is produced by the liver and it helps in the transport and regulation of sex hormones, primarily testosterone, dihydrotestosterone (DHT) and estrogen.
When the SHBG protein binds to sex hormones, your tissues can't use those hormones. Your tissues can only use sex hormones that are "free," which means they aren't attached to proteins, such as SHBG. Changes in SHBG levels can affect the amount of hormone used by the body’s tissues.
In men, SHBG binds to sex hormones like testosterone and regulates their levels in the blood. When SHBG levels are higher , less free testosterone is available for the body to use. However, when SHBG levels are lower, more free testosterone is available. This balance is important for maintaining overall health and hormonal function in men.
In women, SHBG plays an integral role in regulating the levels of bioavailable male sex hormones (androgens) and estrogens circulating throughout the body. SHBG has a higher affinity for the androgens testosterone and DHT, and so with the low SHBG, women may have signs and symptoms related to androgen excess.
Know more about Sex Hormone Binding Globulin
Testosterone Total
The Testosterone Total test measures the level of testosterone hormone in the blood. Testosterone is a steroid hormone primarily produced in the testes in men, although it is also present in smaller quantities in the adrenal glands. In women, it is made in small amounts by the ovaries. It is predominantly associated with male physiology and significantly influences physiological functions in both men and women.
The pituitary gland produces luteinizing hormone (LH), which regulates testosterone production. As testosterone levels rise, LH production decreases, slowing down testosterone production. Conversely, when testosterone levels fall, LH production increases, stimulating testosterone production.
Most of the testosterone circulating in the blood gets attached to two proteins, albumin and sex hormone-binding globulin (SHBG), and some of it remains unattached, called free testosterone. Free testosterone and albumin-bound testosterone are also known as bioavailable testosterone, as they are readily available for the body to use for proper functioning.
Know more about Testosterone Total
Free Androgen Index
Interpreting Free Androgen Index (FAI) results
Interpretations
Answers to Patient Concerns & Frequently Asked Questions (FAQs) about Free Androgen Index (FAI)
Frequently Asked Questions about Free Androgen Index (FAI)
Q. What is the Free Androgen Index (FAI) test?
Q. Why would my doctor recommend the Free Androgen Index (FAI) test?
Q. How should I prepare for the test?
Q. Is fasting required before the test?
Q. What do the results mean?
Q. Are there any risks associated with this test?
Q. How often should this test be done?
Q. Can I have the FAI test if I’m pregnant?
Q. How does Tata 1mg ensure accurate lab test results?
Book a Free Androgen Index (FAI) test at home near me
References
- Free Androgen Index [Internet]. Rochester, NY: University of Rochester Medical Center; [Accessed 21 Oct. 2024]. Available from: https://www.urmc.rochester.edu/encyclopedia/content.aspx?contenttypeid=167&contentid=free_androgen_index
- Al Kindi MK, Al Essry FS, Al Essry FS, Mula-Abed WA. Validity of serum testosterone, free androgen index, and calculated free testosterone in women with suspected hyperandrogenism. Oman Med J. 2012 Nov;27(6):471-4. [Accessed 21 Oct. 2024]. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC3515039/
- Rahmatnezhad L, Moghaddam-Banaem L, Behrouzi Lak T, Shiva A, Rasuli J. Free androgen index (FAI)'s relations with oxidative stress and insulin resistance in polycystic ovary syndrome. Sci Rep. 2023 Mar 29;13(1):5118. [Accessed 21 Oct. 2024]. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC10060256/
- Laurent MR, Hammond GL, Blokland M, Jardí F, Antonio L, Dubois V, Khalil R, Sterk SS, Gielen E, Decallonne B, Carmeliet G, Kaufman JM, Fiers T, Huhtaniemi IT, Vanderschueren D, Claessens F. Sex hormone-binding globulin regulation of androgen bioactivity in vivo: validation of the free hormone hypothesis. Sci Rep. 2016 Oct 17;6:35539. Accessed 02 Apr. 2024]. Available from: [Accessed 21 Oct. 2024]. Available from: Sex hormone-binding globulin regulation of androgen bioactivity in vivo: validation of the free hormone hypothesis - PMC
- Hammond GL. Diverse roles for sex hormone-binding globulin in reproduction. Biol Reprod. 2011 Sep;85(3):431-41. [Accessed 21 Oct. 2024]. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4480437/
- Vesper H, Pirkle J. Total Testosterone-Laboratory Procedure Manual. CDC; [Accessed 21 Oct. 2024]. Available from: https://www.cdc.gov/nchs/data/nhanes/nhanes_11_12/tst_g_met.pdf
- Rivas AM, Mulkey Z, Lado-Abeal J, Yarbrough S. Diagnosing and managing low serum testosterone. Proc (Bayl Univ Med Cent). 2014 Oct;27(4):321-4. [Accessed 21 Aug. 2023]. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4255853/
Other tests
