How does InsideTracker calculate Free Testosterone?

InsideTracker uses the empirical formula by Sartorius (FTZ) which is seen as the most accurate in predicting the free testosterone when compared to gold standard method of measuring it by equilibrium dialysis. Calculating Free T widely depends on the lab that serum testosterone and SHBG are measured in and the FTZ calculation of FT is most accurate when taking this into account and accounting for data from different labs.

If you have Free T from a different lab or in different units, please reach out to our support team and we can add Free T based on the Sartorius formula.