Suspected myasthenia, but tests negative. Is 14% AChR modulating Ab significant?

[ontolome]

Hi everyone,

I am a young woman with occasional mild ptosis, dysconjugate gaze, and frequent vocal weakness. No AChR binding, MUSK, or LEMS antibodies and repetitive stimulation (at 10 a.m. in a cold room on a good day) was normal.

I had 14% AChR modulating antibodies, though. The ref. range is 0-20% loss, so this is considered negative. However I read that normal blood causes no significant AChR loss. Is it evidence, however small, of a real condition? Or is this measurement error?

A mestinon trial was equivocal-- great in the first hours (even my awful posture unexpectedly improved-- I think this is why the neuro asked whether any muscular dystrophies ran in my family, lol) followed by increasingly worse exacerbations whenever the drug wore off. Within a week, I was depending on the drug in order to eat or count higher than 20 in one breath. I returned to my old self within a week of stopping it.

I also have full hypothyroidism with no antibodies, and positive ANA. The vocal weakness has been around for longer than 2 years. My problem is not severe, but I wish I knew what was going on, or at least that it's not in my head. I wondered about a congenital condition, but I have proven autoimmunity.

thanks for whatever insights anyone has to offer, if any!