last fridays blood work

[100%]

From Dr.Crisler
We've given up monitoring serum free testosterone as a biomarker of a male's testosterone metabolism, and we've switched to monitoring bioavailable testosterone.

This is because since the 1980's when the free testosterone tests became available, we've discovered that serum free testosterone too rarely correlated to a male's symptoms of testosterone metabolism - eg: damage tolerance.

On the other hand, since the early 1990's, monitoring of bioavailable testosterone has yielded highly reliable correlation with our testosterone metabolism.

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Total testosterone = testosterone-bound-to-SHBG + testosterone-bound-to-albumin + free testosterone

Bioavailable testosterone = [ testosterone-bound-to-albumin + free testosterone ]

Total testosterone = testosterone-bound-to-SHBG + Bioavailable testosterone

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There are three bioavailable T tests which I recommend to forum members, and they all have different reference ranges:

1) Quest have a calculated BioT test (14966X).



2) Labcorp have a pure measurement BioT test, ie: "Testosterone, Free and Weakly Bound (143255)", and this test does use precipitation to remove the SHBG-bound-to-testosterone component, but it uses RIA (radio-immunoassay) instead of LC/MS/MS to measure the residual BioT component.

Insert 143255 into the "test number" field at the following page:


Labcorp now have a more sensitive Total Testosterone test, ie: "Testosterone, Total, Women, Children, and Hypogonadal Males, LC/MS-MS (070001)".
This test uses LC/MS/MS to measure the total T.

Insert 070001 into the "test number" field at the following page:

....and two tests will be listed not one (not sure why), then click on the number 070001


3) Mayo Labs have a BioT test "Testosterone, Total, Bioavailable, and Free, Serum (83686)", and this test uses precipitation to remove the SHBG-bound-to-testosterone component, but they measure the remaining fraction of BioT using reference samples, radioactive labeling, and a percentage calculation.