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

[madman]

CDC Hormone Standardization Program (CDC HoSt) Certified Estradiol Assays (UPDATED 4/2024)

 

[madman]

Comparability of Free Testosterone Measurements- Results of the Interlaboratory Study

https://academic.oup.com/clinchem/article/70/Supplement_1/hvae106.074/7760719 Assessment of free testosterone (FT) has been recommended as a biomarker for diagnosis and management of hypogonadism and female hyperandrogenism. Reliable laboratory measurements are essential for correctly...

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[madman]

* The data from the present analyses suggest that the interaction of the three sex hormones with their cognate binding proteins is highly complex and dynamic and influenced by their relative circulating concentrations. Therefore, models of testosterones binding to SHBG, based on the assumption of fixed apparent binding affinity of sex hormones with SHBG, that do not consider the influence of estradiol and dihydrotestosterone on the free testosterone fraction are unlikely to provide accurate estimates of free testosterone fraction.

* Because of these complex interactions between various sex hormones as well as other ligands with sex hormone binding globulin, direct measurements of free testosterone using a reliable assay, such as the equilibrium dialysis method, may be a superior marker of testosterone’s treatment effect.

Modulation of circulating free testosterone fraction by T, DHT and estradiol during TRT

The thread discusses the modulation of circulating free testosterone fraction during Testosterone Replacement Therapy (TRT) and its relationship with other hormones. Here are the main points from the discussion: Free Testosterone Fraction: The thread emphasizes the importance of the free...

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* Collectively, these data highlight the non-linear, concentration-dependent modulation of testosterone repartitioning into bound and free fractions by each of the three sex hormones.

*Our finding that the estradiol, DHT, and testosterone interact to alter free testosterone fraction non-linearly suggests that in men with hypogonadism who are receiving TRT, free testosterone levels should be measured using a reliable method to guide the dose titration. The models that do not consider changes in estradiol and DHT concentrations are susceptible to error in estimating free testosterone concentrations.

*These data suggest that changes in estradiol and dihydrotestosterone concentrations should be considered in evaluating response to testosterone treatment because of their differential influence on free testosterone concentrations in addition to their ability to exert other independent biologic effects. Because of these complex interactions between various sex hormones as well as other ligands with sex hormone binding globulin, direct measurements of free testosterone using a reliable assay, such as the equilibrium dialysis method, may be a superior marker of testosterone’s treatment effect.

 

[madman]

CDC Hormone Standardization Program (CDC HoSt) Certified Total Testosterone Procedures (UPDATED 9/2024)


Siemens Healthcare are the only ones with a CDC HoSt Certified TT Chemiluminescence Immunoassays (Atellica IM TSTII, ADVIA Centaur TSTII, ADVIA Centaur CP TSTII, Dimension Vista TTST)!

Siemens Healthineers is the only T immunoassay manufacturer to be currently certified CDC HoST

Authors C. Abou-Diwan1, N. Parker, S. Pagliaro, S. Lewisch, E. Barczak , V. Shalhoub, E. Oduaran, J. Freeman. Siemens Healthineers, Tarrytown, NY, Siemens Healthcare Diagnostics Inc., Tarrytown, NY, Abstract Background The CDC Hormone Standardization (CDC HoST) Certification Program, is...

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Conclusions

The TSTII assay consistently achieved CDC certification from 2019 to 2023, while the TTST assay was initially certified in 2014. Siemens Healthineers is the only testosterone immunoassay manufacturer to be currently certified, the TSTII assay has achieved certification for four consecutive years.

 

[madman]

CDC Hormone Standardization Program (CDC HoSt) Certified Estradiol Assays (UPDATED 9/2024)


Quest Diagnostics still nowhere to be found!

 

[madman]

* The data from the present analyses suggest that the interaction of the three sex hormones with their cognate binding proteins is highly complex and dynamic and influenced by their relative circulating concentrations. Therefore, models of testosterones binding to SHBG, based on the assumption of fixed apparent binding affinity of sex hormones with SHBG, that do not consider the influence of estradiol and dihydrotestosterone on the free testosterone fraction are unlikely to provide accurate estimates of free testosterone fraction.

* Because of these complex interactions between various sex hormones as well as other ligands with sex hormone binding globulin, direct measurements of free testosterone using a reliable assay, such as the equilibrium dialysis method, may be a superior marker of testosterone’s treatment effect.

Modulation of circulating free testosterone fraction by T, DHT and estradiol during TRT

The thread discusses the modulation of circulating free testosterone fraction during Testosterone Replacement Therapy (TRT) and its relationship with other hormones. Here are the main points from the discussion: Free Testosterone Fraction: The thread emphasizes the importance of the free...

www.excelmale.com

* Collectively, these data highlight the non-linear, concentration-dependent modulation of testosterone repartitioning into bound and free fractions by each of the three sex hormones.

*Our finding that the estradiol, DHT, and testosterone interact to alter free testosterone fraction non-linearly suggests that in men with hypogonadism who are receiving TRT, free testosterone levels should be measured using a reliable method to guide the dose titration. The models that do not consider changes in estradiol and DHT concentrations are susceptible to error in estimating free testosterone concentrations.

*These data suggest that changes in estradiol and dihydrotestosterone concentrations should be considered in evaluating response to testosterone treatment because of their differential influence on free testosterone concentrations in addition to their ability to exert other independent biologic effects. Because of these complex interactions between various sex hormones as well as other ligands with sex hormone binding globulin, direct measurements of free testosterone using a reliable assay, such as the equilibrium dialysis method, may be a superior marker of testosterone’s treatment effect.

* The values derived from the random forest model exhibited high level of concordance with the laboratory-measured values of percent free testosterone ( R² 0.78, p= 2.2 × 10-74), confirming the robustness of the analytical model (Figure 1).

 

[madman]

* 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

Key points here!

* While the use of cFT may be of value in preventing misdiagnosis and overtreatment of hypogonadism, it has its limitations. Therefore, reassessing cFT calculators to enhance their accuracy and alignment with equilibrium dialysis measurement of free T is needed. Additionally, standardizing and validating cFT calculators, as well as optimizing available assays for total T and SHBG are crucial steps.




Again something to keep in mind when it comes to using/relying upon the calculated FT methods!

*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

Use of calculated FT in men: advantages and limitations

https://journals.lww.com/co-endocrinology/abstract/2024/12000/use_of_calculated_free_testosterone_in_men_.7.aspx INTRODUCTION Clinical practice guidelines on the diagnosis of male hypogonadism focus on clinical signs and symptoms of androgen deficiency, as well as biochemical assessment of...

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WHAT ARE THE LIMITATIONS OF CALCULATED FREE TESTOSTERONE?

Although free T, if accurately measured, may be physiologically and clinically relevant, the complexity of directly measuring free T limits its introduction into routine clinical practice. Alternatively, clinicians rely on cFT as an acceptable estimate, and thus proxy,of free T concentrations. Existing calculators, including models by Vermeulen, Ly-Handelsman and Zakharov, use calculation methodologies based on total T and SHBG concentrations [3&&]. Free T calculator performance was investigated by comparing cFT values using these three different calculators against measured free T values obtained through the gold standard LC/MS-MS coupled with equilibrium dialysis. The Vermeulen formula appeared to perform best across a wide range of SHBG levels, whereas the Ly-Handelsman model showed significant divergence from measured free T at lower SHBG levels [9]. However, the Vermeulen formula exhibits suboptimal accuracy and tends to overestimate measured free T by 20–30%. Despite this, the current model remains a widely accepted tool for free T calculation due to its ability to integrate a broad range of SHBG, total T and albumin concentrations. This advantage is particularly important in conditions where SHBG concentrations are impacted and/or when total T concentrations are in the borderline range of the lower limit of normal [9].

The use of free T calculators in clinical routine is, however, hindered by a number of imperfections of which clinicians should be aware of when interpreting cFT values (Table 2). Firstly, quality of cFT results depends on the performance of assays used to measure total T, SHBG and albumin. For instance, automated SHBG immunoassays lack standardization[24]. Furthermore, these models are simplified representations of the true binding milieu and may not account for all variables influencing the equilibrium between total and free T, such as SHBG-binding affinity variability and stoichiometry [3&&].

This could particularly be important in men with SHBG polymorphisms. These genetic variations can potentially influence binding affinity between T and SHBG, which is not taken into account in calculators that use a constant binding affinity. In a recent study focusing on the impact of relatively common SHBG single nucleotide polymorphisms (allelic prevalence between 0.5 and 58.2%), healthy men who were heterozygotes for rs6258 had lower serum SHBG levels, while those who were heterozygotes for rs6259, homozygotes for rs727428 and carriers of rs1799941 had higher serum SHBG levels compared to healthy men with wild-type SHBG. These SHBG polymorphisms influenced both SHBG and total T levels, with total T being higher in rs727428 homozygotes and in carriers of rs5934505, rs1799941 and rs6259. Interestingly, these variants did not influence cFT or measured free T concentrations [25&&].

As cFT is a calculated variable, its validity is debated and limited by a lack of standardization and quality control resulting in variable reference ranges. The Vermeulen model, for instance, overestimates free T by 20–30%. Moreover, there is no consensus on a universal cut-off between low and normal cFT values. A thorough review detailing the pitfalls of various methodologies for total and free T assessment was recently published [3&&].

There is a need to enhance the measurement of free T, as cFT values are only approximations. There is also a pressing requirement to reassess current freeT calculators to improve their accuracy and alignment with direct measurement methods. Moreover, additional research is necessary to optimize existing commercially available assays for SHBG, as well as studying SHBG-binding affinity in specific patient groups (e.g. obesity and diabetic individuals) to accurately reflect the true binding environment. Standardizing and validating cFT calculators is also crucial to establish harmonized reference ranges and achieve consensus on cutoff values between low and normal cFT levels. Promising recent developments include the establishment of age-stratified reference ranges for free T in healthy nonobese adult men using the gold standard equilibrium dialysis coupled to LC-MS/MS, showing the expected age-related decline in serum-free T concentrations [26,27]. These efforts represent a significant step towards improving the accuracy of free T measurements and calculations in clinical practice.