Your FT levels are truly much higher than you think!
The calculated method you used is based of of the old linear model.....law-of-mass action Vermuelen which has been shown to be inaccurate.
The newer calculated method TruT Free Testosterone Calculator by FPT
is the one you should be using if you want to truly know what your FT levels are.
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
Here is the Free & Bioavailable Testosterone calculator which is based of of the old linear model.....law-of-mass action Vermuelen.....which you used to calculate your FT.
Using your TT 959 ng/dL, SHBG 42.1 nmol/L and Albumin 4.3 g/dL (mean) than your FT is 20 ng/dL.
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Now using the newer more accurate calculated TruT method.
Using your TT 959 ng/dL, SHBG 42.1 nmol/L and Albumin 4.3 g/dL (mean) than your FT is 33.02 ng/dL (over the top end of the reference range 16-31 ng/dL)
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As you can see your FT is much higher than what the calculated Vermeulen method is showing.
Most men do well having FT in the 25-30 ng/dL range and others may do/feel better having levels in the 30-50 ng/dL range but even than most would never need to be running FT levels as high as 50--->50+ range in order to benefit from testosterone replacement.....let alone some could not tolerate such levels.
You are injecting 150 mg weekly so if the labs you posted are your trough.....7 days after your injection (just before your next weekly injection).....than your peak TT/FT levels will be much higher injecting such dose (150 mg once weekly).
The calculated Vermeulen method is outdated and past due it's time and as stated from the newer research regarding T:SHBG binding.
"Our patent protected, novel TruT™ companion diagnostic framework provides accurate determination of free testosterone concentrations. This algorithm is based on experimental data demonstrating that testosterone’s binding to SHBG is a multi-step process involving an allosteric interaction between the two binding sites on the SHBG dimer. Estimates of free testosterone derived incorporating the allosteric coupling of SHBG monomers within the dimer provide accurate determination of free testosterone without systematic deviation from values obtained using equilibrium dialysis"
