Free testosterone: Two different methods, huge difference in results - help

[thalim90]

Hi I will update with numbers when home as I’m on mobile but I did two different tests from quest on the same blood draw. One was free t equilibrium dialysis (showed right near top of the range) while the other was free t and bioavailable t combined in one test as lc/ms/ms (showed both at very low end of the range) Why such a massive difference in results? Which do I rely on? Am I high testosterone or low? So confused. I ordered a saliva home test from myLABbox.com to try n sort this out and a test from labcorp on equilibrium ultrafiltration free t.

Edit 2/7/23:
All Results from Quest Diagnostics:

05/12/2017 Results:
Testosterone, Free (Equilibrium Dialysis, Quest) - 151.9 pg/mL
Reference Range - 35.0-155.0 pg/mL
Testosterone, Total (LC/MS/MS) - 896 ng/dL
Reference Range - 250-1100 ng/dL

01/26/23 Results:
Testosterone, Free (Equilibrium Dialysis, Quest) - 144.1 pg/mL
Reference Range - 35.0-155.0 pg/mL
Testosterone, Total (LC/MS/MS) - 700 ng/dL
Reference Range - 250-1100 ng/dL

01/26/23 Results:
Testosterone, Free, Bioavailable and Total (MS - all below results MS)
Testosterone Free 76.7 Reference Range - 46-224 pg/mL
Testosterone Bioavailable 161.1 Reference Range - 110-575 pg/mL
Testosterone Total: 670 Reference Range - 250-1100 ng/dL

SHBG doesn't change much on all labs 39-42 Reference range 10-50 nmol/L
Estradiol, Free 1/26/23 Result: 0.47 pg/mL Reference range <or= to 0.45 pg/mL
Albumin 4.6-4.7 Reference range 3.6-5.1 g/dL

 

[Systemlord]

One was free t equilibrium dialysis (showed right near top of the range) while the other was free t and bioavailable t combined in one test as lc/ms/ms (showed both at very low end of the range) Why such a massive difference in results?

You rely on neither test, because it sounds like Quest mixed up your labs with someone else's.

 

[thalim90]

Hmmm. I redid the total free and bioavailable test LC/MS/MS and got similar results. I'm thinking about redoing the free t (equilibrium dialysis) again. I did this same test 8 years ago and got the high end result then too. So there's something up with the test methods for sure. I just don't know which is reliable.

 

[Nelson Vergel]

Where are the results ?

 

[tareload]

Much wider Free Testosterone reference range in recent research on FT levels in healthy young men

Very recent paper from October 2022. I'm not one to push for constant higher Free T levels or the idea that everyone 70 years ago was walking around with 1700ng/dL TT levels, but I thought this was interesting. They used equilibrium dialysis and a nonobese ("healthy") population of men, coming...

www.excelmale.com

Links in this thread should be required reading but so far almost no interest or comments. Should be "stickied".

 

[thalim90]

I edited in my results in the original post and here. Thanks for any insight!

All results from Quest Diagnostics:

Edit 2/7/23:

05/12/2017 Results:
Testosterone, Free (Equilibrium Dialysis, Quest) - 151.9 pg/mL
Reference Range - 35.0-155.0 pg/mL
Testosterone, Total (LC/MS/MS) - 896 ng/dL
Reference Range - 250-1100 ng/dL

01/26/23 Results:
Testosterone, Free (Equilibrium Dialysis, Quest) - 144.1 pg/mL
Reference Range - 35.0-155.0 pg/mL
Testosterone, Total (LC/MS/MS) - 700 ng/dL
Reference Range - 250-1100 ng/dL

01/26/23 Results:
Testosterone, Free, Bioavailable and Total (MS - all below results MS)
Testosterone Free 76.7 Reference Range - 46-224 pg/mL
Testosterone Bioavailable 161.1 Reference Range - 110-575 pg/mL
Testosterone Total: 670 Reference Range - 250-1100 ng/dL

SHBG doesn't change much on all labs 39-42 Reference range 10-50 nmol/L
Estradiol, Free 1/26/23 Result: 0.47 pg/mL Reference range <or= to 0.45 pg/mL
Albumin 4.6-4.7 Reference range 3.6-5.1 g/dL

@Nelson Vergel

 

[sammmy]

The Equilibrium Dialysis result is consistent with the Vermeulen calculator:

14 ng/dL = 140 pg/mL

 

[thalim90]

Thanks sammmy anyone else have any insight?

 

[thalim90]

bump

 

[Cataceous]

You're comparing Quest's equilibrium dialysis test to their calculated method. I'd thought the latter was based on Vermeulen—and the range is about right—but there appears to be a divergence in results here unless there's something peculiar about the SHBG or albumin values. Did they give you the specific results for these? Otherwise I'd be inclined to disregard their result of 76.7 pg/mL and assume that 130-140 pg/mL is what it should be. That's mid-range, which still conflicts with the upper-range ED result. But in either case you're not low. I'm not sure how much clarity you'll get by throwing in a couple of different test methodologies. I'd be more interested in a repeat of the ED/CALC tests.

 

[RickB]

The most important thing is to find a methodology and stick with it. Then you can at least compare your results to prior ones every time.

Certain people hate free t direct, but it's what my original diagnosis was based on, and to me it fits. And though I've done other tests for free t, they are only in addition to free t direct.