Free Testosterone targets for the best Libido

[madman]

I have the opposite issue of Jacb: on 100 mg weekly of T cypionate (divided into 2 weekly doses), my recent (Jan. 2024) Labcorp results show very high T, but rather low free T:

TOTAL TESTOSTERONE: >1500 NG/DL
FREE T: 11.5 (DIRECT)

SHBG wasn't measured on this test, but I assume it's high, thus suppressing free T. I've started taking 10 mg of boron daily in the hope of lowering SHBG and increasing free T.

My libido is OK, but could use a boost.

Any other suggestions welcome!

You did not use the most accurate assays for testing TT (LC/MS-MS) and FT (Equilibrium Dialysis or Ultrafiltration).

Your FT was tested using the known to be inaccurate direct immunoassay which should not be used/relied upon.

You need to have your FT tested using what would be considered the most accurate assays such as the gold standard Equilibrium Dialysis or Equilibrium Ultrafiltration especially in cases of altered SHBG in order to know where it truly sits.

You need to retest your TT (LC/MS-MS) and FT (ED/UF) before jumping to any conclusions as to where your FT level truly sits!

 

[madman]

I have the opposite issue of Jacb: on 100 mg weekly of T cypionate (divided into 2 weekly doses), my recent (Jan. 2024) Labcorp results show very high T, but rather low free T:

TOTAL TESTOSTERONE: >1500 NG/DL
FREE T: 11.5 (DIRECT)

SHBG wasn't measured on this test, but I assume it's high, thus suppressing free T. I've started taking 10 mg of boron daily in the hope of lowering SHBG and increasing free T.

My libido is OK, but could use a boost.

Any other suggestions welcome!

With a whopping TT 1500 let alone >1500 ng/dL you would need to have an absurdly high SHBG as in upwards of 200 nmol/L or well over in order to hit a lowish/low FT!

 

[Ozzieville]

Thanks, Madman - makes sense. On Dr. Peter Attia's podcast, Attia got into this issue with Derek of "More Plates, More Dates": #291 ‒ The role of testosterone in males and females, performance-enhancing drugs, sustainable fat loss, supplements, and more | Derek, More Plates More Dates Pt.2 - Peter Attia.

It's also annoying that Labcorp doesn't provide an exact total T measurement if the T level is above 1500.

Do you happen to know if perhaps Quest uses the gold standard test? And if not Quest, what lab does?

 

[madman]

Thanks, Madman - makes sense. On Dr. Peter Attia's podcast, Attia got into this issue with Derek of "More Plates, More Dates": #291 ‒ The role of testosterone in males and females, performance-enhancing drugs, sustainable fat loss, supplements, and more | Derek, More Plates More Dates Pt.2 - Peter Attia.

It's also annoying that Labcorp doesn't provide an exact total T measurement if the T level is above 1500.

Do you happen to know if perhaps Quest uses the gold standard test? And if not Quest, what lab does?

It's also annoying that Labcorp doesn't provide an exact total T measurement if the T level is above 1500.

This is because you had it tested using the wrong assay the electrochemiluminescence immunoassay (ECLIA) which caps out at 1500 ng/dL.

You would need to use the most accurate assay LC/MS-MS-No upper limit.

070001: Testosterone, Total, Women, Children, and Hypogonadal Males, LC/MS-MS | Labcorp

Labcorp test details for Testosterone, Total, Women, Children, and Hypogonadal Males, LC/MS-MS

www.labcorp.com

Method Used for Total Testosterone:

– Liquid chromatography-tandem mass spectrometry (LC-MS/MS)- No upper or lower limit

– Analytical sensitivity: 1.0 ng/dL

– Analytical specificity: no cross-reactivity with other steroid compounds or supplements like biotin

– Analytical Measurement Range: 1.0 ng/dL to 2,000+ ng/dL








Do you happen to know if perhaps Quest uses the gold standard test? And if not Quest, what lab does?

Labcorp and Quest both offer the most accurate assays for TT (LC/MS-MS) and FT (Equilibrium Dialysis).

Your cheapest option would be using Nelson's discountedlabs which offers the most accurate assays as your blood work will be done through Quest.

Testosterone, Free (Dialysis) and Total, MS

Get an affordable and accurate testosterone test results with our Total Testosterone, M and Free (Equilibrium Dialysis) test. Visit DiscountedLabs.com for more information.

www.discountedlabs.com

Labcorp

1. 500726: Testosterone, Free, Mass Spectrometry/Equilibrium Dialysis (Endocrine Sciences) | Labcorp

Free: equilibrium dialysis; total: liquid chromatography/tandem mass spectrometry (LC/MS-MS)


2. 070038: Testosterone, Free, Equilibrium Ultrafiltration With Total Testosterone, LC/MS-MS | Labcorp

Free: equilibrium ultrafiltration; total: liquid chromatography/tandem mass spectrometry (LC/MS-MS)



Quest Diagnostics

3. Testosterone, Total, LC/MS and Free (Equilibrium Dialysis)

Free: equilibrium dialysis; total: liquid chromatography/tandem mass spectrometry (LC/MS-MS)