Does anyone know if synthroid can cause a false positive in modulating? Has anyone had a positive in all 3 groups? or more than one at one time?
Thanks,
Mike

Mike, I could find absolutely no findings on that. Perhaps Mrs. D. might know more.

MG is a clinical diagnosis that is confirmed with testing. So if someone has all the obvious signs of fatigable weakness plus positive test results, chances are that they have MG.

Yes, some Acetylcholine Receptor Antibodies are positive (false or not) in ALS, in older patients, in some patients with Downs Syndrome, patients taking D-Penicillamine, etc. That is why a good doctor will take the sum of all the evidence before declaring someone has MG.

The three antibodies - binding, modulating and blocking - are not necessarily positive in all MG patients. Some only have binding, some only modulating and some have both.

http://neuromuscular.wustl.edu/mtime/mgdx.html

Antibody titers vary greatly, even for one person. It depends upon what meds you are on, how bad the MG is, etc. Even then, some patients who have severe MG, for example, may have a low titer while someone who is mild may have a high one. MG experts do not go by a ACh antibody test to decide how an MG patient is doing because it's highly variable. A clinical exam, breathing tests and various other tests like arterial blood gases is how a doctor determines how a patient is doing.

Is there a reason you are asking?

Annie

Thanks Annie
I'm posting for my sister. Her Modulating came back positive. Our mom and 2 aunts were DX'ed and of course I was dx'ed (positive binding). She needs to get over her shyness. She has a Dr appt in the morning. I think her doc sent off more bloodwork last visit. Her symptoms below.
1. droopy eye brow
2. one side of face drooping (I think)
3. weakness in legs
4. one arm so weak she can't lift milk out of frig.
5. at times severe tirdness
Mike

Aw, Mike, shyness is sort of cute.

Does anyone else out there have modulating only antibodies, besides Mike's sister and me? 3 - 4% of MGers only have those. I think it's funny how they say 3 - 4 percent. Why don't they get crazy specific and say 3.2 - 4.3 or something. That number is probably higher.

I hope her appt. goes well. Drooping muscles are not normal, neither are weak ones. If she gets worse upon exertion, that's typical of MG. The more you do, the more acetylcholine you need. In MG, not enough acetylcholine gets to the muscles because the "doorway" that it goes through (from the nerve to the muscle) is either blocked by antibodies or destroyed by them.

Let us know how it goes. Or maybe she can!


Annie

I'm on pins and needles till tomorrow. I'm sure as this plays out she will get over that shyness because this board makes you feel like you aren't fighting this alone.
Hugs
Mike

My sisters last visit the Dr did RNS test and the Dr said the results were "abnormal" what the @@@@ does that mean? Her Dr wants single fiber test done at Duke but next available is March. My sisters Dr sent blood work off to Mayo the last batch wasn't sent to Mayo. The local lab thought they could do it. The Dr also set up CT of her Thymus on Tues. also promised meds next visit.

Another development is my sister says she has a photo of our Grandfather in his later years with a droopy eye lid. This saga keeps getting really strange.
Mike

Mike, How is your sister doing? I imagine this is all very overwhelming to her. It was to me at first too. Heck, it still is years later.

An RNS can be positive in lots of disorders, it's not "specific" to MG. If it showed a decrement, meaning that the signal kept going down, then it is indicative of MG (because MG gets worse upon exertion). The RNS sort of simulates "exercise" by "electrocuting" the muscle over and over again.

It's a good idea to send her labs to Mayo, since they invented their antibody test and have found it to be more accurate than other places.

Older people can have ptosis from aging too. But in your family, it may be MG!

It sounds like you guys are getting good care. That's half the battle. Learning all about MG and the things that can make it worse, the drugs, etc. is really important. I hope you'll let her know about things like the MGFA website: www.myasthenia.org

There are probably more families like yours. I have found that my ancestors often didn't talk about their health problems, which I find very unhealthy, and went about their lives no matter what was going on. Damn Norwegians.

Annie

Thanks Annie
She is hanging in there. However she hates all this testing.

The thing about her RNS test was the Dr said it was abnormal. I thought it was positive or negative. That's the problem with these tests none are definitive. Someone is going to have to sit down look at all data and make a decision. They can test you to death and get nowhere.
Mike

I can't believe I'm going to defend a doctor now. They have to do at least the basic testing for MG. I know it's painful. It completely sucks. Been there, done that too much. But they have to do it because while the antibody tests are specific to MG, they need to "see" with an RNS, EMG or SFEMG, exactly what the muscles are up to and if it is generalized MG. Why? Because you don't want to throw immunosuppressants at someone, if they need them, if they don't have MG. That has been done with some people with CMS, the genetic version of MG, which is not an autoimmune disease and does not respond to immunotherapy.

Doctors like to use more than one word for the same thing. It makes them feel smart. Abnormal does mean positive, just like normal means negative.

Sure, doctors sometimes don't have the ping-pong balls to make a decision but I think the way they are going about caring for your sister makes tons of sense. You can't start Mestinon until you get a positive RNS or EMG. However, if her clinical exam is positive for MG, she has the antibodies AND now her RNS is positive, an MG expert would be inclined to give her both the diagnosis and treatment now, at least in my opinion. Would a SFEMG be absolutely necessary? Maybe not. Especially since they think it's okay to wait for FIVE months to get it done. And she would have to withdraw from any meds at that point in order for the test to be accurate.

At her next appointment, she should lay all of this out for the doctor. Maybe she could say, "I have MG antibodies, fatigable weakness and a positive RNS . . . isn't that enough for a diagnosis of MG?" As she coyly bats her ptotic eyelashes.

They are getting somewhere for your sister. Some people have to literally wait years, 40 in my case, to get a diagnosis. So I think her doctors are doing pretty well so far. She needs time to let this sink in anyway, right?

Hang in there. If she gets worse before her next appt., either have her call her neuro or go into the ER, okay?

Annie