Why Total Testosterone May Be Misleading for Low T Diagnosis

[madman]

Dr, Channa Jayasena

 

[madman]

Dynamic regulation of testosterone bioavailability

 

[madman]

In practice free T assessment is:

Free and total T are concordant in most men

Exceptions:

abnormal SHBG

Some drugs

E2 levels?

 

[madman]

All-cause mortality vs Total T or SHBG

 

[madman]

* Worldwide: Lack of assay harmonization

Thread 'CDC STANDARDIZED TOTAL T and ESTRADIOL ASSAYS and soon to be FREE TESTOSTERONE!'

Jan 5, 2019

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 improvements for both total testosterone (TT) and estradiol (E2). Specifically, the among-laboratory bias has decreased from 16.5% in 2007 to 2.8% in 2017 for TT and from 54.8% in 2012 to 13.9% in 2017 for E2. Not only has bias improved, but data...

• madman
• Replies: 87
• Forum: Blood Test Discussion

• 

Total testosterone measurement

Bias of Abbott Assays in UK vs. reference method

 

[madman]

SHBG assays also very (UK)

FT calculation is poorly quantitative

 

[madman]

US is way ahead in the game here!





Summary

 

[madman]

The case for free testosterone



Leen Antonio

Thread 'Re-evaluating the role of Free Testosterone and SHBG'

Sep 2, 2025

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
• hypogonadism; free testosterone; shbg
• Replies: 25
• Forum: Blood Test Discussion

• 

 

[madman]

Free hormone hypothesis

 

[madman]

Alterations in SHBG

Impact of age

Impact of BMI

SHBG mutations in humans

Transgenic mice with high SHBG

 

[madman]

Measured versus calculated Free T

Fairly good agreement between calculated (cFTV) and measured free T direct dialysis method (i.e., ED of undiluted serum against buffer with direct LC-MS/MS assay of FT in the dialysate).

 

[madman]

Free testosterone and sexual symptoms

 

[madman]

Discrepancies between total T and free T

Added value of free T compared to total T

 

[madman]

Free testosterone in the diagnosis of hypogonadism

 

[madman]

CONCLUSIONS

 

[madman]

Thread 'Dr. Shalender Bhasin: Optimizing the Diagnosis and Treatment of Hypogonadism 2025'

Oct 7, 2025

Nelson's house u heard it here first!

Dr. Shalender Bhasin!

* over the past 4 decades he has become a global leader in the biology of androgens, sarcopenia and aging related functional decline, his research has shaped clinical guidelines, its informed public health policy particularly around testosterone therapy, anabolic interventions and then the development of function promoting therapies




Pay attention to 25:40-34:36 of the presentation where he explains the importance of measuring free testosterone using a standardized Equilibrium Dialysis method!

Explains the...

• madman
• hypogonadism; diagnosis/treatment; trt
• Replies: 32
• Forum: Testosterone and Men's Health Articles