A Reappraisal of Testosterones's Binding In Circulation: Physiological and Clinical Implications

[madman]

..........

 

[madman]

Partitioning of testosterone in the systemic circulation



https://academic.oup.com/view-large/figure/94946787/er.2017-00025f1.tif

 

[madman]

Multiple domains of HSA (human serum albumin) are involved in the binding and transport of biomolecules

(a) crystal structure of HSA depicting multiple domains (I to III) of HSA

(b) a linear model of testosterone binding to HSA based on the assumption of 1:1 stoichiometry



https://academic.oup.com/view-large/figure/94946814/er.2017-00025f2.tif

 

[madman]

Schematic Representation of Experimental models of Testosterone Binding to SHGB

(a) linear model of testosterone (T) binding to SHBG as conceptualized by Vermeulan, Sodergard and Mazer

(b) new model (ZBJ, schematic adaptation) proposed by Zakharov



https://academic.oup.com/view-large/figure/94946820/er.2017-00025f3.tif

 

[madman]

Multiple hypothetical mechanisms for the cellular uptake of testosterone and downstream signaling

(a) the model depicting the "free" hormone hypothesis

(b) the megalin dependent mode of testosterone entry

(c) the SHBG receptor-testosterone system

(d) steroid ligand-dependent interactions between SHBG and at least two matrix-associated proteins in the fibulin family



https://academic.oup.com/view-large/figure/94946825/er.2017-00025f4.tif

 

[madman]

Factors contributing to erroneous assumptions of binding affinity and stoichiometry in linear models of testosterone binding to its cognate binding proteins



https://academic.oup.com/view-large/94946811

 

[madman]

Conditions that alter SHBG concentrations



https://academic.oup.com/view-large/94946834

 

[madman]

The relative merits and demerits of various methods of measuring free and bioavailable testosterone levels



https://academic.oup.com/view-large/94946853

 

[madman]

Harmonized reference ranges for Total and Free T levels

Accurate Measurement and Harmonized Reference Ranges for Total and Free Testosterone Levels (2022) Ravi Jasuja, Ph.D., Karol M. Pencina, Ph.D., Liming Peng, MSc, Shalender Bhasin, MB, BS* INTRODUCTION A central tenet of endocrinology is that the hormones secreted by the endocrine glands...

www.excelmale.com

 

[madman]

Improving Diagnostic Accuracy and Treatment Decisions in Men with Hypogonadism

www.excelmale.com

 

[madman]

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

Measurement of Free Testosterone in Serum Using Equilibrium Dialysis Coupled With ID-UHPLC-MS/MS: Comparison Between Equilibrium Devices (2021) Hui Zhou, Ph.D., Ashley Ribera, BS, Amonae Dabbs-Brown, BS, Uliana Danilenko, Ph.D., Hubert W. Vesper, Ph.D. Centers for Disease Control and...

www.excelmale.com

* 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




CDC Hormone Standardization Program (CDC HoSt) Certified Free Testosterone Procedures?

Sooner or later and SHBG to boot!

When the time comes these will be the only free testosterone assays I will recommend for men to use/rely upon when getting blood work done (pre/post-TRT).




*a lab/assay that is certified by the CDC's HoSt Program

The above applies to TT, estradiol, and soon enough free testosterone and SHBG!

 

[madman]

What's Coming? Accurate measurement of total and free testosterone levels for the diagnosis of androgen disorders

Accurate measurement of total and free testosterone levels for the diagnosis of androgen disorders (7/2022) Ezgi Caliskan Guzelce, MD, Clinical/ Research Fellow, Francesca Galbiati, MD, Fellow, Anna L. Goldman, MD, Assistant Professor of Medicine, Arijeet K. Gattu, MD, Fellow, Shehzad Basaria...

www.excelmale.com