I had mine done by Doctors Data, they are out of Washington State I think. It is good to check them, but from what I am told, especially with B vitamins, it can change on a daily basis. B vitamins are water-soluable so they do not stay in your system. I inject a B-complex once a week to be sure I have enough, ask your doctor about
that and save yourself the money you would spend on the testing. D