Free Testosterone Calculation are there different methods.

lanky · Apr 6, 2017

Just a question on Free Testosterone.
Is there a specific test for Free Testosterone? or is it calculated using SHBG and the Albumin reading in your blood.
I see calculation methods using Albumin saying that it is usually binded to testosterone, but how is it known that 100% of Albumin is binded to Testosterone, maybe this is a dumb question I dont know.
I cant seem to find a lab near me that does a free testosterone test, so I feel I'm missing something.

I noticed that some labs that do a free androgen index using Sex Hormone Binding Globulin. I was reading that it is not accurate to use in males, but is used for females.
Do any Docs use this Index regarding TRT?

madman · Apr 6, 2017

http://www.canjurol.com/howidoit-html.php?ID=2382
Not all methods of testing free testosterone are accurate. Some doctors pay no attention to free and prefer BAT ( bioavailable testosterone = FREE T + T WEAKLY BOUND TO ALBUMIN )

CoastWatcher · Apr 6, 2017

Free testosterone - a thicket of confusion made worse by the way labs determine their results. The calculator in the attached is a good, solid rule of thumb method for deriving an idea of how you stand.

Calculating Free & Bioavailable Testosterone

Esq · Apr 11, 2017

CoastWatcher said:
Free testosterone - a thicket of confusion made worse by the way labs determine their results. The calculator in the attached is a good, solid rule of thumb method for deriving an idea of how you stand.

https://www.excelmale.com/forum/showthread.php?3588-Calculating-Free-Bioavailable-Testosterone

I continue to be confused by this issue. Based on my most recent LabCorp numbers, this calculator results in 11.5 ng/dL free testosterone, equating to 1.63% (quite a bit below the 2% to 3% optimal range I see tossed around a lot). This is calculated from total test at 702 ng/dL, SHBG at 52.5 nmol/L, and albumin at 4.4 g/dL.
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The actual LabCorp results for free test (direct) show 17.5 pg/mL with a reference range of 8.7 - 25.1 pg/mL.
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So, two questions. First, if I convert 17.5 pg/mL to ng/dL, I get 1.75 ng/dL, which is significantly less than the 11.5 ng/dL that comes out of the calculator after inputting total test, albumin, and SHBG. Is this just an issue of LabCorp using weird ranges or something?
Second, based on the LabCorp ranges, both total and free test are roughly square in the middle of the reference range. However, as noted above, when using the calculator linked here, I get 1.63% free test which seems rather low.
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I'll note that Dr. Saya did not seem concerned with either my SHBG or free test numbers, but I continue to stew on the issue. I'm having a lot of the standard symptoms, but my natural total test is pretty solid. I just continue to wonder if this could be a free test issue, or maybe I'm overthinking it.