Thank you for your inquiry.
I would not consider the elevated IgG in your patient a contraindication to immunotherapy, and I would not be concerned with the immunomodulatory responses to immunotherapy in this situation. Therefore, I do not think that you need to follow serial total IgG levels. However, with an IgG of 4,000, I would suggest that you assess your patient for monoclonality. With rheumatoid arthritis, it is highly likely that the IgG will be polyclonal, but a simple serum protein electrophoresis, immunofixation, or immunoelectrophoresis would answer the question easily.
Thank you again for your inquiry and we hope this response is helpful to you.
Phil Lieberman, M.D.