NB: This post was split from this thread. @Hip and @Jonathan Edwards This issue still confuses me, and I apologize as I know I have asked about it before! Do you mean that all antibody tests (whether a test from Quest for EBV, or a test from ARUP measuring enteroviruses, or a test from Mayo or Stanford measuring Virus XYZ, etc) are just measuring the level of the antibody response from the immune system? If someone was autoimmune, could their body give a higher response to viruses that they have been exposed to in the past but it does not mean that the virus is currently active? Does this also apply to the level of an autoantibody titer (or do those always measure someone's *current* level vs. a past one)? For example, when my Endo tests me every three months for the two Hashi's auto-abs, or any of my other auto-antibodies (calcium channel, GAD65, etc) those are actually capturing that moment in time (not a past exposure to something)? Is this correct or am I totally off?