Intrinsic factor

[mummytina]

Hi should have asked this question before but does pa mean u have no intrinsic factor or you have but it doesn't work?

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Hi,

A diagnosis of PA is usually made after a blood-test shows to large red-blood-cells (MCV) meaning you have macrocytosis and usually with it low serum B12. A positive diagnosis of PA is achieved by having IF antibodies, but that test seems rather unreliable, so if positive you are most likely to have PA but if not positive it could still mean you have PA. But there are other reasons that can mean you are just B12 def but not specifically have the blood-disorder PA.

See:cks.library.nhs.uk/anaemia_...

And:

cks.library.nhs.uk/anaemia_...

Clarification / Additional information

· Anti-intrinsic factor antibody is extremely specific for pernicious anaemia, but has a low sensitivity (50%). Around half of people with pernicious anaemia will have anti-intrinsic factor antibody [Andres et al, 2004; Longmore et al, 2007]. If anti-intrinsic factor antibody is present, pernicious anaemia is very likely, but its absence does not rule out a diagnosis of pernicious anaemia.

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· Anti-parietal cell antibody is found in 90% of people with pernicious anaemia, but also in 3–10% of people without it [Longmore et al, 2007]. The sensitivity of anti-parietal cell antibody for pernicious anaemia is more than 90%. However, its specificity is 50%, which is much lower than that of anti-intrinsic factor antibody [Andres et al, 2004]. If anti-parietal cell antibody is not present it is unlikely that the person has pernicious anaemia, but its presence is not diagnostic as it can occur in other conditions (e.g. atrophic gastritis) and older people (16% of normal women over 60 years of age) [Carmel, 1992; Hoffbrand et al, 2006].

There are numerous people who test negative and or positive then negative etc for IF antibodies.and or Anti-parietal cell antibody ..its all a bit of a mine field realy...I've tested mildly positive for IF abs some 5 years into B12 treatment, initially negative for Anti-parietal cell antibody , my two grown up kids are on B12 treatment but have tested negative for both, we all still need B12 treatment. There is a lot of new research finding genetic defects that affect B12 absorption, uptake and or transport, methylation etc..so no real answers for most people though, all to new.

Kind regards,

Marre.