Never compare different assays let alone reference ranges from different labs.
When getting blood work stick to using the same lab/assays (most accurate).
Regarding free testosterone, the most accurate assay is the gold Standard Equilibrium Dialysis or Ultrafiltration (next best).
Forget relying on the direct immunoassay or linear law-of-mass action Vermeulen calculated method.
LABCORP:
EQUILIBRIUM DIALYSIS
[URL unfurl="true"]https://www.labcorp.com/tests/500726/testosterone-free-mass-spectrometry-equilibrium-dialysis-endocrine-sciences[/URL]
EQUILIBRIUM ULTRAFILTRATION
[URL unfurl="true"]https://www.labcorp.com/tests/081786/testosterone-free-equilibrium-ultrafiltration-with-total-testosterone[/URL]
NELSONS DiscountedLabs
[URL unfurl="true"]https://www.discountedlabs.com/testosterone-free-dialysis-and-total-ls-ms-ms[/URL]
Look over post #13
[URL unfurl="true"]https://www.excelmale.com/forum/threads/complete-apathy-depression-from-too-high-e2.21596/#post-185169[/URL]
