See the link above. Direct RIA free T method will be 6-7x lower than ED. But some started thinking the units are wrong with labcorp hence they tried to change the pg/ml to ng/dl and say labcorp was using wrong units.
So direct methid correlates well with ED fT but quick check of %fT shows direct fT method way off accuracy wise.
Post in thread ‘Response from LabCorp About Their Incorrect Unit Usages For Their Free Testosterone - Direct - Test’ Response from LabCorp About Their Incorrect Unit Usages For Their Free Testosterone - Direct - Test | Excel Male TRT Forum
BTW:
bixt at EM has a nice comparison of cfTV vs truT.
Post in thread ‘Very high FT on 70mg/wk?’ Very high FT on 70mg/wk? | Page 2 | Excel Male TRT Forum