Bioavailable testosterone

[17chester6]

I have just gone for my three monthly blood work (on T cypionate 60 mg, HCG 500 IU and Arimidex 0.25 mg all twice weekly for the last 18 months). Usually it is the free testosterone that was ordered (among other tests) but now I noticed that it has been left off and instead I am being tested for bioavailable testosterone.

What is the difference and how do the two equate? Any idea why the change?

[2Sox]

This is a pretty good article that will answer your question:

TTFB - Clinical: Testosterone, Total, Bioavailable, and Free, Serum

But basically "bioavailable" is a better reading of the amount of testosterone in your system that is "available" for use. If I understand it correctly, it's a total of what is unbound and circulating - "free" - with what is loosely bound to albumin and readily available.

It's best to ask your doctor why he asked for this test, if you're curious.

[OingoBoingo]

Some doctors feel bioavailable is a better indicator than Free Testosterone.

And there are a few other doctors that are looking for a number somewhere between bioavailable and Total Testosterone.

Good chance we may learn a few more things in the near future.

[17chester6]

I was lazy and posed the question here as you guys are a font of information. I went and looked at the web site for the lab that I attend for blood work and they had a nice simple write up on bioavailable testosterone.
Here is the site:
Bioavailable Testosterone - Physician Overview