How do you use total IgG levels, if at all, to guide plasma exchange for myasthenia gravis exacerbations?

I do not routinely measure total IgG levels before the first and after the last session of PLEX in MG exacerbations, and I do not use this lab to determine the number of required PLEX sessions, but I understand the rationale of the question, and I believe that this topic requires further study. I on...