Free androgen index (FAI) is a ratio obtained after a blood test that detects the testosterone levels. The test measures the levels of total testosterone, free testosterone and a protein called steroid hormone binding globulin (SHBG). The free androgen index measures the testosterone in the blood and compares it with the total testosterone and SHBG in the body. The male hormones called androgens are produced in both men and women. Women with increased androgen levels may be at risk of a condition called polycystic ovarian syndrome (PCOS).
The test is used to determine if an individual has abnormal androgen levels. You may need this test if you show signs of abnormal androgen levels, which differ in women and men.
Males:
300 to 1,000 nanograms per deciliter (ng/dL) Females:
20 to 70 ng/dL
