I have pretty sever MCS along with CFS and cannot tolerate supplements without becoming more ill or have NO effect at all. I am beginning to think this might be due to problems with liver metabolism...with somethings never becoming active (when I take D3 that level ZOOMS up but it never seems to convert to the active form) or "building up" to toxic levels because I can't break them down... I have seen people talking about tests for different types of liver enzymes and was hoping someone could give me specific details - names of tests, how and where to get them..