Free Androgen Index (FAI) - PERLA Health

Free Androgen Index (FAI)

The free androgen index (FAI) is a ratio for testosterone that is calculated after a blood test to find out if you have abnormal androgen levels. This index compares the levels of total testosterone and the levels of a carrier protein called steroid hormone binding globulin (SHBG), to find out the amount of free and active testosterone in your body.


  1. University of Rochester Medical Center. Free Androgen Index. (accessed 3. August 2020)
  2. Pinola P. et al. Androgen Profile Through Life in Women With Polycystic Ovary Syndrome: A Nordic Multicenter Collaboration Study. The Journal of Clinical Endocrinology & Metabolism, Volume 100, Issue 9, 1 September 2015, Pages 3400–3407.

Not sure where to start?

Download our 'Understanding PCOS' eBook!

Your guide in on the way. Check your inbox!