Free androgen index (FAI)
Quick answer: The free androgen index is a calculation from your total testosterone and SHBG levels that estimates how much testosterone is active in your body. Doctors use it to look for high androgen levels in women, for example when PCOS is suspected, and sometimes to assess low testosterone in men.
- SampleBlood
- TakesAbout 5 minutes
- Before the testAn early-morning sample may be requested.
- In fertility careA raised FAI in women can point to PCOS, a common cause of irregular ovulation.
How the test is done
- 1You may be asked to come in the morning
- 2Blood is drawn from a vein in your arm
- 3The lab measures total testosterone and SHBG
- 4The FAI is calculated from these two results
What your results can mean
Reading your report
Hormone ranges differ between labs and by age, sex and cycle day, so discuss your result with your doctor.
If the result is outside the usual range
A high FAI in women can be seen with PCOS and other causes of high androgens. A low FAI in men can be seen with low testosterone.
Who usually has this test
Women with irregular periods, acne, extra hair growth or suspected PCOS, and men with symptoms of low testosterone.
Risks and aftercare
You may have slight bruising at the needle site.
Names and options
Also called: FAI, free androgen index test
Listed by the hospital as
- FREE ANDROGEN INDEX
- FREE ANDROGEN INDEX (FAI)
Questions about this test
Why is FAI used instead of just testosterone?
Much testosterone is bound to SHBG and not active. FAI takes SHBG into account, giving a better idea of active testosterone, especially in women.
Can birth control pills affect the FAI?
Yes. Many pills raise SHBG, which lowers the FAI. Tell your doctor what you take, but do not stop it without advice.
Does a high FAI mean I have PCOS?
Not by itself. PCOS is diagnosed using a combination of periods, signs of high androgens and ovary scans, with other causes ruled out.
Related tests
Tamara Hospital & IVF Centre, Rajajinagar
34/3, 10th Cross Road, opp. Vardhaka Sardar Patel School, 1st N Block, 2nd Stage, Rajajinagar, Bengaluru 560010
The hospital is open 24 hours. Call before you come to check the timing for your scan or sample collection.
Get directions ↗IVF Pulse fertility care at Tamara Hospital →
Reception
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This page explains each test in general terms so you know what to expect. It is not medical advice: your doctor decides which tests you need and what your results mean. Reference ranges differ between laboratories. Updated 4 November 2026.