My IgG levels are low and I don't understand what they mean other than my immune system must be suppressed. One example that is puzzling - I had an IgE test taken to see if I'm allergic to dogs- this test came back negative. But the IgG test on dogs came back high (about 3X the norm). I would think I'm not allergic to the dog, but somehow the dog is affecting my immune system. Does anyone understand how the IgG test and levels affect people with FM and CFS?