False positive

[Zelda123]

Can you have a false positive for pernicious anemia ? My drs seem to think so as a anti body came up in my bloods which can be to do with pernicious anemia.

I have autoimmune thyroiditis and apparently this condition can give a false reading.

[Nackapan]

Not heard of that. Ask them to explain. I thought positive was positive as otherwise what's the point of doing the test?

[Zelda123 in reply to Nackapan]

Exactly and I’ve had fatigue memory issues all sorts of thing have been going on and they won’t re test me.. I asked them and that’s all they said .. when you have autoimmune thyroiditis it can give a false positive 😩

[Nackapan in reply to Zelda123]

For goodness sake. I hope you getting treatment if your B12 low

[fbirder]

My guess is that it is parietal cell antibodies. This used to be a common test for PA but it's not used any more because it gives so many false positives. Around 5% of healthy individuals have low levels of these autoantibodies rising to 10% in older women. They are more common in relatives of patients with autoimmune thyroid disease or gastritis.

[Nackapan in reply to fbirder]

My gp tested for parietal cell antibodies which came back negative. So this test is outdated now?

So is the intrinsic test more reliable? Or is there another?

[fbirder in reply to Nackapan]

The antibodies are found in more than 90% of people with PA. That means you're unlikely to have PA if you test negative. False negatives are rare.

The test is no longer used because of the large number of false positives.

The IFAB test is prone to false negatives.

If you test negative for IFAB and PCAB then you almost certainly don't have PA.

If you test positive for IFAB and PCAB then you almost certainly do have PA.

If you test negative for IFAB and positive for PCAB then it's anybody's guess.

If you test positive for IFAB and negative for PCAB then you probably do have PA. (It is possible to get a positive result for IFAB if you have very high levels of serum B12)

[Nackapan in reply to fbirder]

Okay so I can assume if tested negative for parietal cell antibody. Only test my gp did it's unlikely I have PA . So it's the intrinsic test that can be 50% wrong that's been posted on here not the parietal cell test. Thank you

[Zelda123 in reply to Nackapan]

So if it was a parietal test that came back positive can that be a false positive due having thyroiditis?

[Nackapan in reply to Zelda123]

I'm lost to be honest. Mine came back negative. From what fbirder said that more reliable than if it came back positive as more false positives.

[JanD236]

I think it would be worthwhile asking your gp surgery for a copy of your latest blood tests so that you can see exactly what antibodies you’ve been tested for (parietal cell or intrinsic factor).

It would also be very useful to know what your vitamin B12 blood test showed (level and range).

Perhaps when you have this information you could post them for comments?

Having autoimmune thyroiditis means you are more likely to have PA, not less likely.

[Zelda123 in reply to JanD236]

My drs seem to be funny about giving you the details I don’t know why

[JanD236 in reply to Zelda123]

You’re legally entitled to receive your blood test results. Ask at reception for a print out.

[fbirder in reply to Zelda123]

You should be able to access your records online - nhs.uk/using-the-nhs/nhs-se...

[Zelda123 in reply to fbirder]

I’ve got the patient access app but it won’t let me look at my results ?

[Zelda123 in reply to JanD236]

Parietal seems to ring a bell I think it was that which I had a positive result for

[Ladycroft]

I had no idea that was a thing. Mine tested high positive for parietal cell antibodies I believe the high end of the range was 25 and mine listed 40. My ferritin was also at 5 when diagnosed with the positive