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Positive AMA but negative for M2

I have recently had blood tests done which reveal positive results for AMA and ANA (640 titre) but negative for M2. My liver ultrasound was clear and the only other abnormal blood result was a high GGT (just over 2x upper acceptable limit). I have a hospital consultation soon. Can anyone shed some light on the positive AMA, negative M2 result?

6 Replies

Hi LALsquared

I found this:

Introduction: PBC is almost invariably associated with M2-AMA positivity. We report a series of 4 patients who presented with a PBC-like syndrome, with positive AMA and invariably elevated IgM, in whom the M2 sub-fraction was negative by immunoblot technique. Subsequent external testing for M2 by ELISA was positive

Methods: A retrospective review was performed on 4 patients with cholestatic liver blood tests, with positive AMA and negative M2 sub-fractions by immunoblot. Clinical, biochemical and immunological data was analysed

Conclusions: ELISA assay for detection of M2 sub-fractions in anti-mitochondrial antibody positive patients with PBC-like syndrome is the most sensitive and reliable laboratory technique currently available. Analysis by ELISA should be undertaken in all patients with positive AMA but apparently negative M2 sub-fractions, in whom PBC is strongly suspected clinically.

Maybe they will do a new test that is more sensitive?


Many thanks. My M2 was negative by immunoblot so will ask the consultant about retesting using ELISA assay. I also tested positive for Anti smooth muscle antibody, so can assume there is a possibility of AIH/PBC crossover? Having said that, I also understand that these positive results can also be found in Rheumatoid Arthritis? My mother was a chronic sufferer of this disease. I am symptom free other than the occassional 'itching' on my breast where I had a lumpectomy done in 2005 for breast cancer. I have also found from my research that radiotherapy can cause autoimmune responses. Does anyone have any thoughts on this?


Hi Elpida,

I only just noticed this post while looking for something else. Can you name the source of this info exactly please? For example, give me a direct link to the article, or maybe at least the journal or paper or book the 'paper' was in. I would be ost grateful as I'm really trying to keep on top of all the research, old and new.

Thanks Gritty.

PS If nothing else can you give the year, or title of the piece??


Hi GrittyReads!

It was an article from 2005 from Thieme Connect.


Personally I didn't speculate as to what was going on with myself back in 2010. I started itching persistently early 2010 and 2wks later had had enough so took myself off to see a GP. I had bloods done - LFTs along with FBC - and that started me on the 9mth road to being diagnosed with PBC.

I did stumble across PBC when I was looking up in library ref books and also online. Hoped I hadn't got it but never mentioned to the doctors.

I did have an ultrasound months prior to diagnosis and that according to the hospital doctor on my first consultation was that it all looked pretty much normal. That day he took the antibodies test. I got a copy of his letter to my GP who was left to inform me I had PBC and write out the first prescription for urso Dec 2010. The letter stated that I had a 'high titre' of AMAs but the ANA was negative. Due to my itching and at the time fatigue (I never thought anything of the latter and don't have it any longer), along with the abnormal LFTs and also the GGT that he started to check, with the AMAs he diagnosed me with PBC almost 4yrs ago.

I don't know what the M2 means. I did have other antibodies checks along the way but nothing was positive apparently.

I know had my AMA been negative back in later 2010 the next step would probably have been a biopsy as that can confirm PBC if suspected. I've never had a biopsy nor do I want one either.


Why not get in direct touch with the PBC Foundation, who host this site on 'Health Unlocked'? There is a link to their website at the top of the page, that will give you phone and email links. I think a lot of us on here have not even been told this level of detail and may not be able to advise - and you do need hard facts not opinions.

Good luck and take care of yourself, try not to get too stressed (I know that's easier said than done.


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