What Is A Free Androgen Index?
The Free Androgen Index (FAI) test is a calculated value used to assess the levels of free and active androgens (male hormones, such as testosterone) in the bloodstream. It is derived by dividing total testosterone levels by sex hormone-binding globulin (SHBG) levels and multiplying by 100. The test is essential for detecting hormonal imbalances, particularly conditions such as polycystic ovary syndrome (PCOS) in women or androgen deficiency in men.
This test is primarily ordered when individuals show symptoms of hormonal imbalances, such as abnormal hair growth, menstrual irregularities and decreased libido. By evaluating the ratio of active testosterone to SHBG, it provides valuable insights into conditions that affect androgen activity, such as PCOS, hirsutism, hypogonadism or infertility.
How is the Test Performed?
Free Androgen Index test are usually performed by:
Sample Collection
A healthcare professional takes a small blood sample from your arm.
Lab Analysis
The blood is analyzed in the laboratory to measure levels of total testosterone and SHBG. The FAI is then calculated using these values.
Results
Test results are typically available in 24 to 48 hours.
What are the symptoms that prompt this test?
The test is used to identify underlying causes of the following symptoms:
Men
- Reduced sex drive or erectile dysfunction
- Loss of muscle mass
- Fatigue or low energy levels
- Development of breast tissue (gynecomastia)
- Symptoms of andropause or hormonal imbalances in elder patients
Women
- Irregular or missed periods
- Excessive facial or body hair (hirsutism)
- Acne or oily skin
- Difficulty conceiving (infertility)
Children
- Early or delayed onset of puberty
- Unusual growth patterns
What are Normal Ranges for This Test?
Male – The Free Androgen Index typically ranges from 30 to 150.
Female – The Free Androgen Index typically ranges from 0.7 to 8.6.
FAI levels vary a lot according to age, sex and medical condition. Make sure to provide complete information to your healthcare provider before taking the test.
**The above-given reference value is for general guidelines only and should not be considered as a diagnosis. Results may vary from one lab to another due to the method of test used. Your healthcare provider will give you the correct interpretation of the results. **
What Happens if Test Results Show Abnormal Levels?
Abnormal FAI results indicate a need for further evaluation:
- Elevated – High FAI levels in women may point to conditions like PCOS, adrenal hyperplasia, or androgen-secreting tumors. In men, elevated levels may suggest androgen resistance.
- If Low – Low FAI levels in men may indicate hypogonadism or pituitary dysfunction, while in women, it could suggest increased SHBG levels or other hormonal imbalances.
Your doctor may order additional tests such as LH, FSH, or DHEA-S to investigate the cause further. Imaging studies, such as pelvic or testicular ultrasounds, might be recommended to identify underlying issues. Treatment options, including hormone replacement therapy or medications to manage symptoms, will be discussed.
