Response from LabCorp About Their Incorrect Unit Usages For Their Free Testosterone - Direct - Test

[Nelson Vergel]

Someone else complaining about this issue:

Did LabCorp Mess Up My Results?

A little background info… 26 years old, feel like shit most of the time. I work out 2-3 a week, have a stable job, am in school, but something doesn’t feel quite “right” (all the symptoms of low-t… fatigue, lethargy, don’t really care about anything, anxiety, fear of life, of doing things...

forums.t-nation.com

 

[jacb]

That is debatable. Free testosterone is NOT fully proportional to T dose. As dose increases, the relative increase of free T is larger due to decreases in SHBG.

OK so best to disregard the LabCorp Free T‘ result and calculate the Free T‘ using, Total T’, SHBG and Albumin from the same group of tests. That in turn raises issues since the online Free T’ calculators seem to come up with different Free T’ values for the same input!

Which online calculator do you favour?

EG Balance My Hormones, Tru-t etc etc?

 

[Cataceous]

That is debatable. Free testosterone is NOT fully proportional to T dose. As dose increases, the relative increase of free T is larger due to decreases in SHBG.

Proportionality exists regardless of SHBG if one assumption is true: The law of mass action is the only significant driver of the consumption rate of testosterone. If this holds then the consumption rate is directly proportional to free testosterone. Clearly at steady state the dose rate on average must equal the consumption rate. Therefore free testosterone is directly proportional to dose rate.

It doesn't matter if SHBG drops with increasing dose. This affects the rate of increase of total testosterone, not free. Free testosterone must rise linearly with the dose.

 

[Nelson Vergel]

Responses of different doses of testosterone injections on body composition, strength, etc.

Comment: 125 mg per week was the lowest dose that provided statistically significant changes in lean body mass and fat mass. PAPER ATTACHED Testosterone dose-response relationships in healthy young men. Bhasin S, et al. Am J Physiol Endocrinol Metab. 2001 Dec;281(6):E1172-81. Full paper...

www.excelmale.com

 

[Cataceous]

Responses of different doses of testosterone injections on body composition, strength, etc.

Comment: 125 mg per week was the lowest dose that provided statistically significant changes in lean body mass and fat mass. PAPER ATTACHED Testosterone dose-response relationships in healthy young men. Bhasin S, et al. Am J Physiol Endocrinol Metab. 2001 Dec;281(6):E1172-81. Full paper...

www.excelmale.com

...

Looks pretty linear.

 

[tareload]

Response from LabCorp About Their Incorrect Unit Usages For Their Free Testosterone - Direct - Test

I've been irked for a year by the apparent incorrect unit usage for the particular Free Testosterone test mentioned above. I periodically reach out to whatever relevant executive I can find. No luck for months until the below correspondence. In brief his explanation doesn't hold up in my view...

www.excelmale.com

See this post plus 5 links attached therein for some bedtime reading.

 

[aloetard]

LabCorp reports free testosterone that do not make sense even in their "direct" method that goes along with LC/MS.

070195: Testosterone, Free, Direct With Total Testosterone, LC/MS-MS | Labcorp

Labcorp test details for Testosterone, Free, Direct With Total Testosterone, LC/MS-MS

www.labcorp.com

Example:

View attachment 12602

Free testosterone is around 2% of total testosterone.

In this example, Total Testosterone is 435.8 ng/dL

Two percent of that is 0.02 x 435.8 nd/dL= 8.72 ng/dL= 87.2 pg/mL (units used for free T)

His Free T was reported as 16 pg/mL which is absurd.

Here is an example from Quest (for this test Testosterone, Free, Bioavailable and Total (Upper Limit T 1,500 ng/dL) plus SHBG)


View attachment 12603

This is the total Testosterone by LC/MS and free T by dialysis

Testosterone, Free (Equilibrium Dialysis) and Total, MS - Most Affordable and Accurate Test

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

View attachment 12607



Quest has a reasonable range AND units.

I have emailed LabCorp several times about this but they ignore it. Dr Saya has done the same thing.

Definitive explanation if you are interested...

A Cautionary Tale...

The endocrinologist I went to just told me that everything was in the reference range and therefore there was nothing to treat (which is infuriating of course...). I was infuriated too with similar conversations before I knew better. F around and find out. If you are dead set on running...

www.excelmale.com

Example in goriest of details....

Calculate Free Testosterone with TruT by FPT

The idea of SHBG as a sponge that sucks up large amounts of testosterone and leaves your free T low doesn't seem to be how it really works. The way I understand it, high SHBG makes your meager production (revealed by the free T) look like it's normal or even high when it isn't. The SHBG is...

www.excelmale.com

Calculate Free Testosterone with TruT by FPT

The idea of SHBG as a sponge that sucks up large amounts of testosterone and leaves your free T low doesn't seem to be how it really works. The way I understand it, high SHBG makes your meager production (revealed by the free T) look like it's normal or even high when it isn't. The SHBG is...

www.excelmale.com

In particular see part II for Labcorb direct FT assay.

If in 100 years 1 person reads this and it helps them understand the situation, then I did truly succeed.