Need help about AMA versus M2 test and my r... - PBC Foundation

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Need help about AMA versus M2 test and my results


Can ANYONE here please tell me the difference between an AMA test and an M2 test. they are not the same. I tested positive 2 times with the M2 and tested negative for AMA. My liver specialist told me that he goes by the AMA and since it was negative and I have no other abnormal liver labs or symptoms and i had an MRCP - mri of my biliary ducts and everything was normal that he thinks I DO NOT have PCB.

Is there a reason that I would have a positive M2 besides PCB? Please write back - you all know all about this and I just joined and am puzzled.

I went to the doctor complaining of upper right sided abdominal pain. That's why he tested me. Also I am ANA and smooth muscle actin negative.


13 Replies

Hi there

The only thing I have read is that m2 with a positive AMA is specific for pbc. I ama m2 positive and have had pbc for 6 years diagnosed by liver biopsy.

Hope this helps

I am opposite to you positive ama negative m2 strange disease

I can tell you there are 9 codes for AMA. (Think it’s 9). M2 is the once that suggests PBC.

I saved a link from Mayo Clinic. M1 - M9

Hi Gwillistexas is right.

There are about 9 different sub-types of antimitochondrial antibodies.

AMA stands for 'antimitochodrial antibodies' while the various suffixes, eg AMA-M1, or (the main one in the case of indicating PBC) ... AMA-M2, and then AMA-M3 ... and so on.

As far as I know, health people, even Drs, talk generally about AMAs, but each sub-type (eg M-1, M-2, M-3, etc) codes for / is involved in the cause of, different types of autoimmune condition.

AMA-M2 is the sub-type that is most linked with the presence of PBC, so if your blood tests show that you have AMA-M2 in your blood, then they will have done all other tests to see if you have PBC. However, some people can have PBC without having AMA-M2 present. Meanwhile, others (like me, and probably you ...) can have AMA-M2 (in my case, at a high level) without having PBC. AMA-M2 is a strong indicator for PBC, but it - alone - is not enough for a diagnosis of PBC. This is where a lot of medics (more so, in the past) have gone wrong and just assumed PBC when AMAs/AMA-M2 are present.

However, according to Blood Donor statistics, about 10% of the UK population have AMAs, but only about 1.5% of these will go on to develop PBC. It has been known that I have AMA-M2 since 1992, but I still don't have PBC ... and I'm still in perfect (well ... I'm getting old!) health. I have annual blood tests to check my liver function, and so far all has been clear, and I still have no signs of PBC.

If your Dr has done all the other tests for PBC, and there are no signs of it, then it seems possible that you are one of the people who 'just' have AMA-M2. You should have your liver function tests (lfts) done every year, for life, from now on ... plus, if you get any symptoms of PBC, go to your GP and ask for extra lfts to be done - my GP always does it straight away. In your case, with the ANA etc I guess you are already checked regularly.

Also, your Drs should have tested you for other possible autoimmune conditions (I was checked for lupus, sjorgrens & others) especially those linked to other sub-types of AMA. You should also be checked for other liver conditions, but it sounds like your Dr has been thorough. NB - For a diagnosis of PBC, you have to have at least 2 out of 3 tests that clearly show PBC: eg: 1) AMAs-M2; plus: 2) abnormal liver function tests (lfts) that are typical of PBC; ... and if there is doubt after these 2 (eg: if you have symptoms of PBC, such as: severe itching, joint and muscle pain, fatigue, etc, but no abnormal lfts), then: 3) a liver biopsy.

If you are still worried, check out the website of the 'PBC Foundation' who host this site on 'Health Unlocked' ... there is a link to the site at the top of this page. There are also phone/email details to talk to their trained advisors, as well as some PBC info on the site. If you join - it's free - you get full access to the site, which has masses of up-to-date info, as well as a detailed summary of the formal diagnostic procedure that should be followed to check for PBC. The 'PBC F' works in close conjunction with the UKs leading PBC Specialists, who regularly write in their 3-yearly magazine. I saw one of the leading PBC experts when a 'new-to-me' Dr tried to say I did have PBC, and he was wonderful.

Sorry it's so long, but I hope this helps, ... and ... enjoy yourself!! Have fun, do things you love, treat yourself. Stress is the worst thing for all autoimmune issues, so engage in some serous fun and de-stressing.

Take care, Gritty

Madamec1 in reply to GrittyReads

I like your philosophy, have fun, treat yourself, no stressing. I got stressed with BT yesterday and put the phone down as I realised it was no good for me. Result of that call was aches & pains in my bones for the rest of the day for first time. Won’t happen again😡

Just to add to Gritty's good reply that here in the UK, doctors usually request a batch of tests be carried out called an autoimmune profile and this includes the anti-mitochondrial antibody level (or AMA test). If the anti-mitochondrial antibody level or AMA test comes up positive or borderline, the lab that did the test will go on to carry out the more specific M2 test. To quote the lab that did my tests, anti-mitochondial antibodies are SUGGESTIVE of PBC, M2 antibodies are more SPECIFIC for PBC. As has already been said, M2 is a sub-type of AMA.

To get a negative AMA and a positive M2 result is odd and I guess that both tests were actually asked for at the same time instead of the M2 following on. (As all tests cost money, each individual test either has to be requested or is an automatic consequence.) Your doctor may have asked the lab that did the tests for an explanation of the results. If he hasn't, you could always ask him to and then ask for a copy of the explanation. Doesn't do any harm? May be a very simple explanation.

The choice it seems, is to trust your liver specialist's judgement or get a second opinion (and another batch of tests) from a different liver specialist. If you see a different liver specialist, they may however, support the opinion and actions of your current specialist. But getting a second opinion may give a bit more peace of mind and prevent a puzzle niggling in your mind!

AMA is I believe all types M1-9 and I read some where is over all a better indicator. M2 is more specific for pbc. I’ll try to find that other article.,

I seem like you. Have AMA but normal LFT’s. Was told I had PBC then told I can’t have because no itching. My symptoms are fatigue and nausea. In the meantime they’ve found a pineal gland tumour!

GrittyReads in reply to Joel31

Hi, I would read my reply/post above, and the one added by Badpiglet.

In my (not-so-humble) opinion, anyone who tells you that you cannot have PBC just because you are not itching, seriously needs to read the recent UK publication on the official guidelines for the diagnosis of PBC. You can get a summary from the 'PBC Foundation', who host this website here on 'Health Unlocked' - there is a link to the 'PBC F' website at the top of this page.

There are other significant symptoms as well as itching, and not everyone has the itch. Also, you should be checked for other conditions, if AMAs are noted, plus you need to have lfts tested every year. If the symptoms are not resolved once the pineal gland tumour has been addressed, then ask for more checks.

Take care.

Joel31 in reply to GrittyReads

Thankyou !

Hi Erosen, I am exactly the same as you. My AMA was negitive but my AMA M2 is positive. I'm so confused! I switched doctors and have been waiting to see a hepatologist. I go in tomorrow to have a fibroscan done. I'm so nervous. But all my other bloods were fine except slightly elevated LFT. I think I have a fatty liver too. Keep me posted on anything you find out and I'll do the same.

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