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Testosterone-to-SHBG Ratio (Free Androgen Index)

Reproductive Health
Published:
December 5, 2025

Author: MyHealthspan Team

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Testosterone-to-SHBG Ratio (Free Androgen Index)

Why is the Testosterone/SHBG Ratio important for your Healthspan?

The Testosterone/SHBG Ratio provides important insight into your hormonal balance and its impact on Healthspan. An imbalance in this ratio, whether too high or too low, can be associated with symptoms of hormonal excess or deficiency. Maintaining an optimal ratio supports physical function, energy levels, and overall vitality, which are important for long-term well-being.

What is the Testosterone/SHBG Ratio?

The Testosterone/SHBG Ratio, also known as the Free Androgen Index (FAI), is a calculated value obtained by dividing your Total Testosterone level by your Sex Hormone Binding Globulin (SHBG) level. Total Testosterone is the full amount of testosterone in your blood, both bound and unbound. SHBG is a protein that binds to testosterone, rendering it inactive and unavailable for your body's cells to use. The ratio provides a more accurate estimate of how much testosterone is freely available to tissues compared to just measuring total testosterone. A high ratio indicates that more active testosterone is available, which can be particularly relevant in women, as it may suggest excess androgen activity.

How do we take action?

If the Testosterone/SHBG Ratio is found to be outside the typical range, one should consult with a healthcare provider to investigate the underlying causes. An imbalanced ratio can be influenced by various factors, including underlying medical conditions. For example, a high ratio in women is often associated with conditions like Polycystic Ovary Syndrome (PCOS). Strategies to help balance the ratio frequently include lifestyle modifications such as engaging in regular physical activity, maintaining a healthy body weight, managing stress, and optimizing sleep quality. Addressing underlying medical conditions that affect hormone levels is also important. Regular monitoring of this ratio can help guide interventions to support hormonal balance and overall Healthspan."

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https://www.myhealthspan.com/articles/testosterone-shbg-ratio-free-androgen-index