How to co relate RIA and equilibrium dialysis reports

[Omi7276]

I don't have equilibrium dialysis assay in my country and they test free testosterone with RIA or CLIA method only
So my recent free testosterone (RIA method) was 49 pg/ml ( 12-40 pg/ml)
This says I am over the reference range . Should I take this for face value or assume the assay is flawed ?
Is there any way or equation to co relate or convert these levels in equilibrium dialysis levels/range?

 

[Cataceous]

I would not trust those immunoassay methods at all; they are notoriously inaccurate, to the point of being meaningless. Instead, measure total testosterone, SHBG and albumin. Then use the Vermeulen calculator. The range for normal young men is something like 8-23 ng/dL. I believe there is a scale factor that can be applied to Vermeulen FT to make it comparable to equilibrium dialysis.

 

[Omi7276]

Problem is that they use same RIA method for SHBG and total testosterone as well . So I guess everything becomes unreliable now. Lol

Btw does RIA gives exaggerated values compared to equilibrium dialysis ?

 

[Cataceous]

RIA for SHBG and total testosterone is fine. These tests are accurate enough in most cases. I should amend my response above to say that properly done RIA can be accurate, as demonstrated here, but you may not be able to evaluate whether yours was done right. Thus I would still consider Vermeulen FT the most robust way to monitor free testosterone. Note that in the study they found "Numerical values for RIA were approximately one seventh of EqD values." In other words, in the best case RIA is measuring some proxy for free testosterone that is reasonably linear with free testosterone.

 

[madman]

I don't have equilibrium dialysis assay in my country and they test free testosterone with RIA or CLIA method only
So my recent free testosterone (RIA method) was 49 pg/ml ( 12-40 pg/ml)
This says I am over the reference range . Should I take this for face value or assume the assay is flawed ?
Is there any way or equation to co relate or convert these levels in equilibrium dialysis levels/range?

You would need to have your FT tested using an accurate assay such as the gold standard Equilibrium Dialysis or Ultrafiltration especially in cases of altered SHBG to know where it truly sits.

No on should be using/relying upon the direct immunoassay especially in cases of altered SHBG.

Seeing as you do not have access to the most accurate assays (ED/UF) then you would need to use/rely upon the linear law-of-mass action cFTV which is available online for free.

Keep in mind as of now cFTV tends to overestimate when compared to a standardized gold standard ED assay.

Also keep in mind that Quests /Labcorps let alone any of the other labs Equilibrium Dialysis or Equilibrium Ultrafiltration assays in the US or any other country are not standardized!

Top it of that there is no harmonized reference range to boot!

In an ideal situation TT and SHBG should be tested using the most accurate assays but you can nitpick when it comes to low vs high TT let alone assays currently available for SHBG.

I will put it to you like this you can be rest assured that if you have low or normal SHBG and you are hitting a high-end trough TT then your trough FT would be high/very high!

 

[Omi7276]

RIA for SHBG and total testosterone is fine. These tests are accurate enough in most cases. I should amend my response above to say that properly done RIA can be accurate, as demonstrated here, but you may not be able to evaluate whether yours was done right. Thus I would still consider Vermeulen FT the most robust way to monitor free testosterone. Note that in the study they found "Numerical values for RIA were approximately one seventh of EqD values." In other words, in the best case RIA is measuring some proxy for free testosterone that is reasonably linear with free testosterone.

Sorry, I didn't understand the complexity of your last sentence . Are you trying to say RIA gives exaggerated values as compared to equilibrium dialysis ?

 

[madman]

Take home points:

*Assays that are standardized are designed to provide accurate results, traceable to “true” value-assigned certified reference materials and gold-standard reference methods. Results obtained using standardized methods can be compared across assays, institutions, populations, and past and future test results, thereby improving diagnosis, treatment, and outcomes of patients

* Limitations of using free testosterone by equilibrium dialysis and calculated free testosterone concentrations in practice are the lack of assay standardization, an accuracy-based quality control program, and a harmonized reference range. Until these limitations are addressed, free testosterone by equilibrium dialysis and calculated free testosterone should use reference ranges established by individual laboratories or their specific assay method

Testosterone Assays

Testosterone Assays (2022) Brendan King, MD, Caleb Natale, MD, Wayne J.G. Hellstrom, MD The accurate detection and quantification of serum testosterone levels are necessary for the diagnosis of hypogonadism in men, evaluation of endocrine abnormalities, and monitoring and titration of...

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CDC STANDARDIZED TOTAL T and ESTRADIOL ASSAYS and soon to be FREE TESTOSTERONE!

How the CDC Clinical Standardization Programs Are Improving Hormone Tests - AACC.org WHAT PROGRESS HAS CDC MADE WITH STANDARDIZING TOTAL TESTOSTERONE AND ESTRADIOL TESTS? Since HoSt began in 2010, CDC has had more than 350 participants in 15 countries. Participants have shown measurable...

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Key Points:

* Limitations of using free testosterone by equilibrium dialysis and calculated free testosterone concentrations in practice are the lack of assay standardization, an accuracy-based quality control program, and a harmonized reference range. Until these limitations are addressed, free testosterone by equilibrium dialysis and calculated free testosterone should use reference ranges established by individual laboratories or their specific assay method

*Currently, the CDC is developing a harmonized method for free T based on calculated free T using REVISED FORMULAE. This may bring the measurement of free T to a referable standard in clinical laboratories and common reference intervals that all clinicians can use

*Assays that are standardized are designed to provide accurate results, traceable to “true” value-assigned certified reference materials and gold-standard reference methods. Results obtained using standardized methods can be compared across assays, institutions, populations, and past and future test results, thereby improving diagnosis, treatment, and outcomes of patients




The Need to Harmonize Clinical Laboratory Test Results-----

Laboratory test results are a critical component of patient care. These values help physicians diagnose disease and are critical to developing clinical guidelines that direct treatment options and are instrumental in ongoing efforts to improve and measure the quality of patient care. Most tests report a numeric value for healthcare providers to interpret and the range of numbers reported for a test for a certain condition may vary depending on the method used

Different test methods, however, may report different numeric values for the same condition. Although these test results may be accurate within the context of its own method, this variation can create confusion for physicians and patients. Clinical laboratory test results need to be harmonized so that healthcare providers and the public receive the same numeric result regardless of the method or instrument used or the setting where it was performed




post #11

Direct Measurements of Free Hormones Using Mass Spectrometry-Based Methods

Only at Excel, are we gonna take you deep! Clinical Utility and Analytical Aspects of Direct Measurements of Free Hormones Using Mass Spectrometry-Based Methods (2022) Mark M. Kushnir, Heather A. Nelson, and Kelly Doyle Background The free hormone (FH) hypothesis states that hormone...

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*Equilibrium dialysis (ED) followed by LC-MS/MS is considered the gold standard methodology

*FH concentrations measured by UF-based methods often do not agree with ED-based methods because of UF conditions (temperature, time, centrifugation speed), the type of the UF device (MWC membrane material, material of the of the housing, seal around the membrane, etc.), and inconsistencies in the filtration rate. Therefore, reference intervals are typically not interchangeable across methods for measurement of the same FH

 

[Cataceous]

Sorry, I didn't understand the complexity of your last sentence . Are you trying to say RIA gives exaggerated values as compared to equilibrium dialysis ?

They're saying that the RIA method they tested gives numbers that are a factor of seven smaller than the results from equilibrium dialysis. So arguably RIA is measuring some parameter that correlates well with actual free testosterone, but you have to multiply by seven to get the correct estimate for free testosterone. You can somewhat see this in play with your own measurement. The units are pg/mL, and 10 pg/mL = 1 ng/dL. Your value of 49 pg/mL is 4.9 ng/dL, which would be low, considering that free testosterone is on the order of two percent of total testosterone. So clearly at a minimum some multiplicative factor must be applied to put the absolute numbers closer to reality. Since you don't know the correction factor for this test you can only rely on the reference range. Calculated free testosterone avoids a lot of this complexity, because different assays for total testosterone and SHBG don't vary as severely as those for free testosterone do.

 

[Omi7276]

They're saying that the RIA method they tested gives numbers that are seven time smaller than the results from equilibrium dialysis. So arguably RIA is measuring some parameter that correlates well with actual free testosterone, but you have to multiply by seven to get the correct estimate for free testosterone. You can somewhat see this in play with your own measurement. The units are pg/mL, and 10 pg/mL = 1 ng/dL. Your value of 49 pg/mL is 4.9 ng/dL, which would be low, considering that free testosterone is on the order of two percent of total testosterone. So clearly at a minimum some multiplicative factor must be applied to put the absolute numbers closer to reality. Since you don't know the correction factor for this test you can only rely on the reference range. Calculated free testosterone avoids a lot of this complexity, because different assays for total testosterone and SHBG don't vary as severely as those for free testosterone do.

My SHBG is 22 And total testosterone 5.72 ng/ml but these are tested with ECLIA method . Can they be used as valid entity in calculator ?

 

[Cataceous]

My SHBG is 22 And total testosterone 5.72 ng/ml but these are tested with ECLIA method . Can they be used as valid entity in calculator ?

Yes. Using a default albumin of 4.3 g/dL, your Vermeulen FT is 15.2 ng/dL, which is mid-range for healthy young guys.

 

[Omi7276]

Yes. Using a default albumin of 4.3 g/dL, your Vermeulen FT is 15.2 ng/dL, which is mid-range for healthy young guy

Thanks a lot