I had an AChR antibody test several months after I presented with symptoms of MG. I was retested about 2-3 years later. Both of these tests were negative. However, I know of others who tested negative early on and positive later. It sounds like a good idea to have the testing done again.

Also...having a negative antibody test (whether it's 1 month or 10 years since start of symptoms) does not exclude the diagnosis of MG. Others have been diagnosed with a positive EMG test. I was diagnosed with positive tensilon test and clinical symptoms.

My insurance company readily approved appropriate treatments for my MG, including IVIG, even in the absence of a positive antibody result.

I hope you find some answers soon. If you are not already being evaluated by a neuromuscular specialist that'd be a good idea. A neuro ophthalmologist is also important to see if you are having eye symptoms (double vision, droopy eyelid).

Cate