Understanding Free Androgen Index: Normal vs Optimal Ranges

?What is Free Androgen Index?

The Free Androgen Index is a calculated ratio that reflects the proportion of free (unbound) testosterone relative to sex hormone-binding globulin (SHBG), expressed as a percentage. It is derived from total testosterone and SHBG levels and provides insight into the bioavailable androgen activity in the body. This marker is particularly useful in assessing hormonal status in women and in conditions where SHBG levels may be altered.

!Why It Matters

The Free Androgen Index can be associated with various hormonal imbalances and may suggest conditions such as polycystic ovary syndrome (PCOS) in women or hypogonadism in men. A higher FAI could indicate relatively more free, biologically active testosterone, while a lower FAI may suggest reduced androgen availability. This marker helps clinicians understand androgen status beyond total testosterone alone, which is particularly important when SHBG is abnormal.

Reference Ranges

Lab normal ranges may vary between laboratories. Optimal and longevity targets are based on research literature and should be interpreted with your physician.

Symptoms of Imbalance

• Irregular or absent menstrual periods
• Unwanted facial or body hair growth (hirsutism)
• Male pattern baldness or hair loss
• Difficulty conceiving or infertility
• Fatigue or low energy levels

How to Improve Your Levels

• 1Maintain a healthy body weight through balanced diet and regular exercise
• 2Reduce refined carbohydrate and sugar intake to support hormonal balance
• 3Manage stress through meditation, yoga, or other relaxation techniques
• 4Ensure adequate sleep (7–9 hours per night) to support hormonal regulation
• 5Consider inositol supplementation if PCOS-related, under medical guidance
• 6Consult a healthcare provider to address underlying conditions or medication side effects

When to Test

Free Androgen Index should be tested when investigating symptoms of hormonal imbalance such as irregular periods, hirsutism, or infertility. It is commonly ordered as part of the evaluation for suspected PCOS in women or hypogonadism in men. Testing is also appropriate when total testosterone levels are unclear or when SHBG is known to be abnormal.

Related Biomarkers