I recently had tests done at Labcorp:
Total T -------- 693 ng/dL
Free T --------- 11.6 pg/mL
SHBG ---------- 50 nmol/L
So when I go to the online free testosterone calculator, and plug in Total T and SHBG, and leave albumin at the default 4.3, the calculator says I have free test of 11.8 ng/dL, which it says is 1.71% of total. At first that seemed really close, except that the units don't look right. The Labcorp free test is in pg/mL, but the calculator gives ng/dL. Making the conversion, my 11.6 pg/mL is 1.16 ng/dL, and that's 0.17% of total. So while it looks close at first, the calculator and the actual results are off by a factor of 10.
I'm having trouble making sense of this. The reason it's important is because I had total and free tests done four years ago, but did not have SHBG tested:
Total T -------- 763 ng/dL
Free T --------- 17.1 pg/mL
and I was hoping to calculate what SHBG must have been, assuming 4.3 for albumin. But it looks like everything is off by a factor of 10. What am I doing wrong here?