Intrinsic factor

[Lurcher-lady]

Looking at recent blood results my intrinsic factor is 1, which doc says is fine, says it should be below 1.2 U/ml. I self Inject now as spray/tablets don’t help. Do I need to ask for the test to be done again? I don’t like to waste resources.

[fbirder]

The IF antibody test is a bit useless as 50% of people with PA give a negative result.

[wedgewood]

You are already saving resources by self-injecting to keep yourself well . If you didn’t do that , you would eventually become so unwell , and be down at the surgery, being prescribed pharmaceutical drugs for some of the symptoms.

I don’t think that your GP will sanction another IFA very soon after your first one . Medichecks do one which costs about £100.00 in total ( you need a venous blood sample taken , not a pin-prick one ) You need to take a break from B12 injections before an IFA Test ( couple of weeks at least )

[Lurcher-lady in reply to wedgewood]

Thank you both

[wedgewood]

You obviously have B12 deficiency symptoms , or you wouldn’t be injecting successfully . You have already discovered that sprays and tablets don’t help your symptoms . Your GP should now assume that you have PA . Even a negative IFA result does not rule out PA , as all GPs should know . And you have a positive IFA result , but it isn’t quite positive enough for your GP! Has your GP read the very latest information on Pernicious Anaemia ?

[fbirder in reply to wedgewood]

Unfortunately, it's not quite as simple as that.

Whenever an analytical chemist makes a measurement there will be some noise in the signal they are measuring. Especially if it's a really small signal, like measuring IF antibodies.

So even when the antibodies aren't present there will still be something to measure. If the something is very small then we can't tell if it's a real signal or just noise - so we label it negative. If there's a signal large enough to be (almost) certainly not noise then we label it positive. Here's a diagram - frankhollis.com/temp/Signal...

[wedgewood in reply to fbirder]

Thanks for that . I’m always pleased to learn something new . But inspite of that information , I think that what Lurcher-lady has experienced indicates that she has P.A as we know a high percentage of PA patients test negative for the IFA test , which she has apparently done , but finds that tablets and sprays don’t help her symptoms, but b12 injections do .

I have read of PA patients who have tested negative for IFA , then a short time later have tested positive . It’s all so frustrating . I feel so lucky that I immediately tested positive .

I once read that someone thought that if a subject had suffered with PA for a long period , that the IFA would disappear , because they had done their job and totally eliminated the Intrinsic factor production . I find that hard to believe and cannot imagine if that is a possibility from an analytical chemist’s standpoint .

I struggle on to try to understand the enigma that is Pernicious Anaemia . Best wishes .

[fbirder in reply to wedgewood]

Oh! Absolutely she has PA.

The reason a lot of people test negative is because their signal isn't big enough to distinguish from the noise. And that will depend a lot on just how noisy the assay is being that particular day. At least that's my guess, I don't really know exactly how these ELISA assays work.

I can't really see the immune system stopping production of the antibodies. It's very good at hiding its weapons for years and years. That's why you can be exposed to an antigen and then suffer a severe reaction to a second exposure decades later.

[wedgewood in reply to fbirder]

Thank you fbirder .