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Author Topic: Free T Calculation From Total T and SHBG valid ?  Direct Measurement superior?  (Read 2953 times)

doin it

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July 2016
Journal Of Endocrinology

 http://m.joe.endocrinology-journals.org/content/230/1/R13.long?view=long&pmid=27113851#sec-1

1)  There are SHBG "variants"

2)  "The mathematical models used to calculate free plasma androgen or estrogen levels currently rely on SHBG measurements obtained using immunoassays (Vermeulen et al.1999), and they are based on the assumptions that all SHBG molecules react similarly immunologically and have identical steroid-binding properties. These assumptions are fallible, however, because some SHBG variants are not recognized in immunoassays, while others have abnormal affinities for sex steroids (Wu & Hammond 2014), including the SHBG P156L variant with a reduced affinity for testosterone that is present in ~1% of Caucasians, and increases the free fraction of testosterone in the blood of male carriers (Ohlsson et al. 2011)".

This may be further confounded as different labs use different methodologies for SHBG measurement.

Also suggests that there could be different affinities for different ethnic groups.

Additionally, immunoassays are, in some cases, known to be inaccurate.

3)  "These findings highlight the pressing need for sensitive mass spectrometric methods to measure both total and free sex steroid levels in the blood."

4)  "...They also illustrate the limitations of current methods for measuring their plasma concentrations, which are used in algorithms to calculate free steroid levels, and highlight the need for more direct methods to measure plasma free steroid concentrations..."

So, is Direct Free T Measurement Superior to a calculated value ?

Among the several interesting topics in this paper:
"Despite the large number of SHBG measurements performed for diagnostic purposes, it is remarkable that there have been only two reports of complete SHBG deficiencies in humans .. "
(went on to describe the symptons)

Cataceous

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So, is Direct Free T Measurement Superior to a calculated value ?

Not using the standard methods. There's a paper showing just how flawed these are in comparison to using the calculated values. Clearly, as with estradiol, mass spectrometry is the way of the future. But prices must come down, and reliability must improve. One forum member recently related that he did use this (expensive) method and that it agreed with his calculated value.
I am not a medical doctor; any suggestions are meant to be discussed with your doctor.
Age: 60, Ht: 5'10", Wt: 154 lbs
Protocol: 3.2 mg TE subQ qd, 2.4 mg TP subQ qd, 20 mcg GnRH subQ 5.25x/d, 6.25 mg DHEA bid, 12.5 mg enclomiphene qod
Approximate levels (peak): TT: 700 ng/dL, E2: 30 pg/mL, DHEA-S: 300 ug/dL, SHBG: 30 nMol/L

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doin it

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Can you provide the link showing "just how flawed these methods are" ?

Re:
"reliability must improve",

Are you saying that measuring methods must get better than mass spectrometry (MS) ?  MS would be just as accurate for one substance (Testosterone) as another (Estradiol).
And Tandem MS (LC-MS/MS), aka "sensitive"), is even more accurate than MS.  And everyone agrees that LC-MS/MS is the gold standard for Estradiol.

Re:
"Not using the standard methods"

And so, you are challenging the paper, saying that the "standard methods" that are based on Immunoassy, with all Its faults, is superior to LC-MS\MS ?

Re:
"...this (expensive) method..."

You DO get what you pay for !

I guess if you want ACCURATE Testosterone test results, you have to pay for it like with Estradiol.


Re:
" One forum member recently related that he did use this (expensive) method and that it agreed with his calculated value.:

How does the statistical argument go, "if you throw a ball at a solid wall, it will finally go through the wall and not bounce off it...

Cataceous

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Can you provide the link showing "just how flawed these methods are" ?

A Critical Evaluation of Simple Methods for the Estimation of Free Testosterone in Serum

Quote from:  doin it
Re:
"reliability must improve",

Are you saying that measuring methods must get better than mass spectrometry (MS) ?  ...

No, I'm saying the MS methods must improve. To wit: “It needs to be noted that mass spectrometry assays are highly complex and require both a high degree of manual adjustments and controlling of operational conditions. Therefore, a high level of skill and knowledge is required to properly set up and operate these methods. Inappropriately operated mass spectrometry methods can lead to profoundly incorrect and inconsistent results. To facilitate the implementation of mass spectrometry in the clinical laboratory, the Clinical and Laboratory Standards Institute (www.CLSI.org) is developing a series of guidance documents, with one specifically addressing methods for steroid hormones. Furthermore, organizations such as the American Association of Clinical Chemistry (www.AACC.org) are offering training opportunities on mass spectrometry for the clinical laboratory.”

Quote from:  doin it
Re:
"Not using the standard methods"

And so, you are challenging the paper, saying that the "standard methods" that are based on Immunoassy, with all Its faults, is superior to LC-MS\MS ?

Calculated is better than the immunoassay methods, which have vastly different ranges at different labs, and which seem remarkably unstable in practice.

Quote from:  doin it
Re:
"...this (expensive) method..."

You DO get what you pay for !

I guess if you want ACCURATE Testosterone test results, you have to pay for it like with Estradiol.
...

The paper you cite, though interesting, is still short of saying that SHBG measurements are going to be a problem for many guys. So for now I'd rely on calculated free T rather than pay a lot of money for an MS-based test, which could have been botched anyway.
I am not a medical doctor; any suggestions are meant to be discussed with your doctor.
Age: 60, Ht: 5'10", Wt: 154 lbs
Protocol: 3.2 mg TE subQ qd, 2.4 mg TP subQ qd, 20 mcg GnRH subQ 5.25x/d, 6.25 mg DHEA bid, 12.5 mg enclomiphene qod
Approximate levels (peak): TT: 700 ng/dL, E2: 30 pg/mL, DHEA-S: 300 ug/dL, SHBG: 30 nMol/L

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doin it

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By saying:
 "No, I'm saying the MS methods must improve."
and
 "To wit: “It needs to be noted that mass spectrometry assays are highly complex and require both a high degree of manual adjustments and controlling of operational conditions. Therefore, a high level of skill ...",

AND

"So for now I'd rely on calculated free T rather than pay a lot of money for an MS-based test, which could have been botched anyway."

you ARE, by the same token, saying that Estradiol (E2) LC-MS/MS tests are unreliable ???

(Which is at odds with accepted wisdom !)


Re:
" Calculated is better than the immunoassay methods, which have vastly different ranges at different labs, and which seem remarkably unstable in practice."

We are NOT talking about measuring steroids by Immunoassay, we are talking about LC-MS\MS.

Re:
" The paper you cite, though interesting, is still short of saying that SHBG measurements are going to be a problem for many guys."

You must have misunderstood the paper, it IS saying that steroid measurements based on calculations that are based on Immunoassays ARE "fallible" (for ALL guys) !

doin it

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Cat,
Putting aside both our arguments above, I now believe the paper is REALLY saying that SHBG "Variants" change SHBG test results not because of measurement accuracy methodology but because of personal (individual) DNA variants that are outside conventional SHBG measurement sensitivity ranges.

Meaning that some guys read low on SHBG tests because of SNPs.

And that one should narrow down the SNP that is in error so that as steroid technology marches on, the SNP can be corrected via CRISPR-Cas9/13, Base Editors, etc.
(If indeed, it is found that high SHBG should be "corrected")

And that future SHBG measurement tests should test for SHBG SNP variants, not a "shotgun", "one size fits all" approach.

Cataceous

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you ARE, by the same token, saying that Estradiol (E2) LC-MS/MS tests are unreliable ???

Yes, the MS E2 test is more likely to be completely wrong and I've fallen victim to it myself. In one instance it returned a value in the mid-20s when the correct reading was over 50.

Quote from: doin it
Re:
" Calculated is better than the immunoassay methods, which have vastly different ranges at different labs, and which seem remarkably unstable in practice."

We are NOT talking about measuring steroids by Immunoassay, we are talking about LC-MS\MS.


We're clearly talking about both, as the paper you posted about is critical of immunoassays, and promoting use of mass spectrometry.

Quote from: doin it
You must have misunderstood the paper, it IS saying that steroid measurements based on calculations that are based on Immunoassays ARE "fallible" (for ALL guys) !

The misunderstanding is yours. "Fallible" says nothing about the frequency and amount of incorrectness. Every test is fallible. The example cited involves an unquantified issue with one percent of caucasians, which is not a huge concern.
« Last Edit: January 18, 2018, 07:36:47 pm by Cataceous »
I am not a medical doctor; any suggestions are meant to be discussed with your doctor.
Age: 60, Ht: 5'10", Wt: 154 lbs
Protocol: 3.2 mg TE subQ qd, 2.4 mg TP subQ qd, 20 mcg GnRH subQ 5.25x/d, 6.25 mg DHEA bid, 12.5 mg enclomiphene qod
Approximate levels (peak): TT: 700 ng/dL, E2: 30 pg/mL, DHEA-S: 300 ug/dL, SHBG: 30 nMol/L

Cataceous

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...
And that future SHBG measurement tests should test for SHBG SNP variants, not a "shotgun", "one size fits all" approach.

The main thrust is that they want a transition to mass spectrometry for measuring free and total hormones: "These findings highlight the pressing need for sensitive mass spectrometric methods to measure both total and free sex steroid levels in the blood."
I am not a medical doctor; any suggestions are meant to be discussed with your doctor.
Age: 60, Ht: 5'10", Wt: 154 lbs
Protocol: 3.2 mg TE subQ qd, 2.4 mg TP subQ qd, 20 mcg GnRH subQ 5.25x/d, 6.25 mg DHEA bid, 12.5 mg enclomiphene qod
Approximate levels (peak): TT: 700 ng/dL, E2: 30 pg/mL, DHEA-S: 300 ug/dL, SHBG: 30 nMol/L

doin it

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Beaten into submission...

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