Immediate Test Change
Test Update – Testosterone, Free and Total (TFTEST)
Effective September 12, 2024.
Beginning September 12, 2024, Testosterone, Free and Total (TFTEST) will be sent to a different reference laboratory due to an emergency inactivation at the current reference laboratory because of reagent problems.
This follows an extended test delay since April of this year.
Please contact Client Services with any questions or for assistance.
For specimens ordered and collected before September 12, 2024, but not received by Mayo before September 12, 2024, Mayo will send them to LabCorp for testing. When available, those results will be uploaded as scanned documents to the lab order.
Test Change Overview
Testosterone, Free and Total (TFTEST)
As part of this change, the test’s name has been modified to clarify its contents and how it is performed. Test name changes for the other testosterone assays are planned for later this fall.
New Test
Old Test
Test Name
Testosterone, free and total, by equilibrium ultrafiltration mass spectrometry
Testosterone, Free and Total
Performing Laboratory
LabCorp
Mayo Clinic Laboratories
Methodology
Equilibrium ultrafiltration; Liquid chromatography/tandem mass spectrometry
Equilibrium dialysis; Liquid chromatography/tandem mass spectrometry
Specimen Collection
Serum, 2.2 mL
Red (No Additive) Tube
Serum, 2.5 mL
Red (No Additive) Tube
Minimum Volume
1.8 mL
1 mL
Transport Temperature
Ambient
Refrigerated
Turnaround Time
5-7 days
4-8 days (delay as of April 19, 2024)