Using the newer calculated method
TruT Free Testosterone Calculator if one had a
TT level 600 ng/dL or less along with an
SHBG of 55 nmoL/L than they would definitely have sub-par
FT levels 18.01 ng/dL reference range 16-31 ng/dL
View attachment 7565
In your case with a TT of 880 ng/dL and an SHBG of 55 nmoL/L than using the newer calculated method (TruT™ provides the most accurate estimates for free testosterone)
TruT Free Testosterone Calculator by FPT than your
FT level is near the top end of the range 28.94 ng/dL reference range 16-31 ng/dL
View attachment 7566
People need start understanding that all of these other equations whether
linear law-of-mass action models or empiric equations are flawed!
Current problems with accurate free testosterone determination
Current methods for measuring free testosterone (fT) are technically challenging and not accurate. The widely used direct immunoassay and tracer analog techniques for measuring fT have been shown to be inaccurate. Equilibrium dialysis, the reference method against which other methods are compared, is labor-intensive and cumbersome, and therefore has had limited clinical adoption. As an alternative, free testosterone can be computed from the total testosterone, SHBG, and albumin concentrations. Recently, Endocrine Society’s Expert Panel acknowledged the experimental problems in fT measurements and concluded that "...the calculation of free testosterone is the most useful estimate of free testosterone in plasma..."
However, we have demonstrated that even the calculated fT values derived from the prevailing equations, based on linear law-of-mass action models or empiric equations, differ systematically from free testosterone measured by equilibrium dialysis by as much as 40%.
Why TruT™?
The only FDA-registered free testosterone calculator
- Improved biophysical characterizations have suggested the importance of models that consider allosteric coupling of testosterone with dimeric SHBG. This model, as implemented by TruT™ provides the most accurate estimates for free testosterone.
- Commonly available free testosterone calculators (issam.ch, nebido.com, pctag.uk) use models of testosterone:SHBG binding (proposed by Vermeulen et al. and Sodergard et. al) which were developed before the crystal structure for SHBG:T complexes were available. These models assume that the two SHBG monomers behave identically in binding testosterone. Detailed experimental data show that the "simplified linear model is erroneous." References.
- The Endocrine Society has issued position statements which highlights the laboratory- and operator-dependent variability inherent in direct free testosterone measurements. For this reason they advocate for indirect "calculator" based methods References.
- The TruT™ calculator provides the ideal solution by using measurements of total testosterone, SHBG, and albumin to calculate free testosterone while taking into account the complex, non-linear allostery in SHBG's association with testosterone. TruT™ is the only calculator available that uses this more complex formulation. References
Forget relying on the older
calculated methods let alone
direct immunoassay and tracer analog techniques.....either pay to have the gold standard equilibrium dialysis or ultrafiltration or better yet do not spend the money and simply use the newer calculated method TruT Free Testosterone Calculator by FPT
People tend to go on and on and on about high SHBG resulting in low FT.....sure when TT levels are sub-par or low but when TT levels are high enough even with a higher SHBG one can still have healthy FT levels.
Even with an SHBG of 70,80.90 as long as TT is high enough one can have a healthy FT.
In your case although most would consider an SHBG of 55 nmol/L high seeing as your TT (trough) is fairly high 880 ng/dL than your FT of 28.49 ng/dL is right near the top end of the reference range of 16-31 ng/dL and keep in mind this is using the newer calculated method
TruT™ which provides the most accurate estimates for free testosterone.