Free & Bioavailable Testosterone calculator

**Kryptonite_10** · 07-16-2007, 04:55 PM

Subject: Free & Bioavailable Testosterone calculator

Thought this was pretty cool.

http://www.issam.ch/freetesto.htm

Obviously, you need to have detailed blood work done to do the calculations. Something I also found interesting was that many labs calculate 'free testosterone' levels differently. Not all methods are equal in accuracy. Just something to keep in mind when reviewing your blood work.

**Kryptonite_10** · 07-16-2007, 04:57 PM

The gold standard methodology for measurement of free testosterone is considered by many investigators to be equilibrium dialysis.

In this method a sample of serum with radiolabelled testosterone added is placed in a chamber and dialysed across a membrane that blocks the transfer of albumin and SHBG. The percentage of free testosterone that is dialysed across the membrane can then be calculated. Absolute free testosterone can be derived from this and total testosterone measurement. This method is influenced by dilution of the hormone to be measured and also relies on being able to measure total testosterone accurately. Furthermore, it is labor intensive and expensive, and not feasible for clinical practice.

It is generally recognized that the Sodergard equation can be reliably used to calculate free testosterone if total testosterone, albumin and SHBG are know.2,3 Again, this requires a reliable determination of total testosterone, and SHBG and albumin are quantified by routine methodology.