Pernicious Anaemia Society
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Weak positive IFA

Hi all,

I've just called my doctors for the results of my intrinsic factor antibodies test and been told it's weak positive. Apparently it's been sent back to the lab for further tests/interpretation but the receptionist couldn't tell me what. Does anyone have any experience of this? What does this mean? It's been a battle to get this far so I'm worried this will mean more of a battle to get injections as it's not a straightforward result.

Thanks

Cathy

6 Replies
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I wrote about the poor reliability of this test, about 1 week ago. It appears that GP's do not know or understand the vagaries of the test. This might be as good as it gets. Getting retested could produce a false negative or apositive.

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Yeh I'm hoping they don't insist on a repeat test. My understanding is (correct me if I'm wrong) that the issue with the test is around false negatives not false positives. Am I right in thinking then that as my test was positive I should be treated for PA for life now with injections? I'm worried I may have a battle as whilst I have loads of symptoms and previously b12 levels as low as 149 currently it is about 280 thanks to self supplementation. As a result the gp is adamant it's normal and my labs cut off levels for deficiency are very low at 130 :(

Reply

Hi,

Are you a PAS member?

pernicious-anaemia-society....

PAS tel no +44 (0)1656 769 717 answerphone available

The PAS might be able to point you to info on IFA test.

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The test method has real problems distinguishing between a low level of anti-bodies and no antibodies - most methods will have this problem but generally this point is well outside the range that it is trying to measure but this isn't the case for IFA.

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So having just obtained a copy of the results for a private appointment it turns out my gastric parietal cell result was weak positive and I am not awaiting a result for intrinsic factor antibodies. I don't quite know what to make of this as a few eeeks previously I had the same test and it was apparently negative. The lab seem to have insisted on doing it again as they won't do IF as a first line test. Is the GPC test unreliable as well?

Reply

yes GPA is prone to false positives and is no longer recommended as a test for PA by WHO and this is reflected in current guidelines for the UK but it may be different in other countries

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