Dr. Betty Murray explains that free testosterone isn't directly measured. Instead, clinicians use the Free Androgen Index (FAI), calculated as total testosterone divided by SHBG times 100. In perimenopausal women, FAI above 5-6 often causes hair thinning, acne, and facial hair growth.
Now, free testosterone can be measured, right? And this is, this is calculated. And most of the time it's a calculated free, it's not an actual measure. And so if we have what they call the free testosterone and free androgen index, it's also known as FAI. You can calculate this by taking your total testosterone and divide it by SHBG, right? Get your SHBG and then multiply that by 100. It's a quick calculated, and we want this optimal FAI under 4. Uh, in PMOS, we'll often see above 5 to 6. Which will also often have hair thinning, acne, maybe chin hair and mustache growth, all of those things. So if you're 4 and above, this could be a really, really interesting thing to understand because this may be driving things.
