Re-evaluating the role of Free Testosterone and SHBG

[madman]

We do it big here at Nelson's stomping ground!

Dr. Leen Antonio (UZ Leuven)!

She has collaborated with the heavyweights in the field Dr. Bhasin and Dr. Jasuja (Brigham and Women's Hospital)), Dr. Fiers and team (UZ Ghent) on research related to free testosterone.

 

[madman]

Free hormone hypothesis

 

[madman]

Free hormone hypothesis

 

[madman]

Alterations in SHBG

 

[madman]

Impact of age and BMI

 

[madman]

Impact of age

Impact of BMI

 

[madman]

Polymorphisms in the SHBG gene

 

[madman]

SHBG mutations in humans

 

[madman]

Equilibrium Dialysis/Ultrafiltration

* Technically difficult and expensive

* Not widely available (widely available in the US)

* Reference range not fully established




Methods to measure or calculate free T

Measuring free testosterone

 

[madman]

Calculated free T (Protein binding dynamics or empirical) e.g. Vermeulen, Ly, Zakharov

* Different calculation models

* Variable accuracy (+ve bias)

* Affected by rare SHBG variants

* Method-specific reference range




Methods to measure or calculate free testosterone

Calculating free testosterone

 

[madman]

Comparison of % Free T

 

[madman]

Immunoassays

* Inaccurate, not valid for male T range




Methods to measure or calculate free T

 

[madman]

Calculated Free T: Realities and imperfections

 

[madman]

Assessing free testosterone: why?

 

[madman]

Discrepancies between total T and free T

 

[madman]

Poor performance of total T to predict low free T

 

[madman]

Incident secondary 'hypogonadism' is associated development of new or worsening symptoms

 

[madman]

Hypogonadism diagnosis: guidelines

 

[madman]

Total T is first line test for diagnosis of male hypogonadism in practice guidelines

 

[madman]

Free testosterone in the diagnosis of hypogonadism