Would be interested in this also. I also have Hashimotos, but only recently found out. Have been on Synthroid for 15 years, no one ever mentioned antibodies. I took an on line test myself after a routine MRI for neck arthritis showed nodules on my thyroid. My neck arthritis is the least of my worries now. I have been seeing a functional doctor, who has been helpful, but leery to take ALL the supplements. He talks about leaky gut and food sensitivities, which I tested positive for IgG and casein. It does make my nose stuffy and feel better without dairy. I would think my immune system is already making too much IgG, so would this IVIg make matters worse?