I just got back from my yearly physical, and along with the standard blood work and urine tests, I asked for a test for “free and total testosterone” since I have some symptoms of low testoterone. My GP basically said “we don’t test for that. We test for FAI, or free androgen index.”
I guess I have a couple of questons:
Is the test useful?
What will it tell me about my level of free testosterone?
Thanks in advance for any insight.
Free Androgen Index is calculated by the following: Total T (nmol/L) / SHBG (nmol/L) x 10. It is also called the Free T index, and it basically gives you a ratio of total T to SHBG (which makes T biologically inactive). T that is attached to SHBG (sex hormone binding globulin) is unable to penetrate the cell membrane and bind with androgen recpetors in the cell, thus eliminating T’s anabolic effect.
Therefore, high Free T (molecular form or weakly bound to albumin) or FAI indicates that there should be more circulating biologically active T in the blood, which is good.
For more info, here’s a PDF link that has excellent info.
Hope this helps.
Kent
Great link Kent
Kent,
You made me feel like I was back in grad school (after reading your post).
Shudderrrrr!!!
Great info.