Testosterone (Total & Free)
What it is
Total testosterone measures all of the testosterone circulating in your blood, while free testosterone measures the smaller portion that isn't bound to carrier proteins and is actually available for your tissues to use.
Why it matters
Total testosterone alone can be misleading because the proteins that bind it, primarily SHBG, vary from person to person, so two people with the same total testosterone can have meaningfully different amounts actually available to their body. Testosterone affects far more than libido: it plays a role in muscle mass, bone density, mood, and energy, which is why unexplained fatigue or changes in body composition are often worth checking against it rather than assumed to be normal aging.
Testosterone (Total & Free) is one of the markers in Zaro's Signal panel and every tier above it.
This information is for educational purposes and is not a substitute for professional medical advice. Always talk to a physician about your specific results and health history.
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