What does it mean if i am a female, have normal estrogen, testosterone & tsh, but low sex hormone binding globulin?

Nothing - u r normal: Regardless of gender, if your estrogen, testosterone & TSH are normal, then you're normal. Sex hormone binding globulin is used to bind up sex hormones, exactly what it says. Sometimes we check both total hormone as well as free hormone, since it's typically free hormone that accounts for benefit claimed by hormone. But rather than look at numbers, consider how you feel. We treat patients, not #s.