Free Testosterone Lab Measures Different for Quest and LabCorp

[T_Eden]

Can someone tell me what the customary measure (in units) is for Testosterone, Free (Direct)?

Here's the deal. I got two different measures from Lab Corp and Quest Diagnostics. Why is the measure of Free Test listed with different scales and units.

Lab Corp (9/29/2017)
Testosterone, Serum - 331, ng/dL, (range 264-916)
Free Testosterone (Direct) - 6.2, pg/mL (range 7.2-24.0)


Quest Diagnostics (1/5/2018)
IMMUNOASSAY
Testosterone, Total - 693, ng/dL, (range 250-827)
Testosterone, Free - 137.3 pg/mL, (range 46.0-224.0)
Testosterone, Bioavailable - 246.5 ng/dL, (range 110.0-575.0)

WHY WOULD THE TWO LAB COMPANIES HAVE SUCH WIDELY DIFFERING RANGES FOR Free Test????

What's going on? Different testing methods?

Thoughts?

 

[Nelson Vergel]

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