I believe all antibodies fluctuate over time. I have other autoimmune diseases and when diagnosed with them my ANA, AMA and ASMA were both very high. are now normal. The fluctuation of the Antimitochondrial Antibody made the diagnosis of Primary Biliary Cirrhosis difficult. I was finally diagnosed with PBC by liver biopsy.

When I was diagnosed with myasthenia, binding, blocking, modulating and MUSK antibodies were all negative. I strongly tested positive to a tension test and because of that the diagnosis of Myasthenia Gravis was made (EMG was borderline). My neurologist explained to me that there are most likely many more antibodies involved in myasthenia which they are unable to test for at this time.

Good luck, hope this helps