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Positive gastric parietal antibody test but normal B12

Mburland profile image

I have an autoimmune condition called Frontal Fibrosing Alopecia ( a variant of Lichen Planopilaris). My dermatologist suggested a few blood tests then wrote to my gp saying that they demonstrated low folate and vitamin D deficiency plus I had a positive gastric parietal antibody test and asked that the GP follow up by organising supplementation. I received a copy of this letter two months later and as I had not heard from GP asked to have an appointment. The GP said as she had not received a copy of the blood results that I needed further blood tests. She tested me for plasma B12 and full blood tests. My B12 came out as normal. She prescribed me high dose vitamin D and folic acid. Gp dismissed my concern over positive gastric Parietal test. I am very confused as to why I would have a positive gastric parietal antibody test but normal B12 and if so what action if any I should take . Think Plasma B12 test may not be accurate enough so thinking about having Private B12 tests at Viapath clinic. I am permanently exhausted and have some foggy memory moments and some muscle pain but nothing very specific but just want to know if I have pernicious anaemia or the risk of developing it.I have requested a copy of the original blood test results to see what exactly I was tested for. If anyone has any experience of this please let me know. I feel very confused.

7 Replies

The GPC antibody test is no longer recommended because it produces too many false positives, especially amongst older people. So a positive result does not mean that you have PA, just that you might have PA.

Mburland profile image
Mburland in reply to fbirder

Thanks. Think I might get more reliable B12 test even if just to rule out pa

Foggyme profile image
FoggymeAdministrator in reply to Mburland

Mburland. A serum B12 or active B12 test does not test for PA. The test for this is called IF antibodies. This test is not a particularly reliable test since 40%-60% of those with pernicious anaemia test negative (though a positive test does indicate PA.

Here's more information about the IF test:


Basically, PA is an autoimmune condition that prevents the production of intrinsic factor, which is needed by the body to enable absorption of B12 from diet.

I note that you have one autoimmune condition and autoimmune conditions can tend to arrive in clusters, so you do have a higher likelihood of also having PA (though this is not a certainty). So it's worth asking your GP to test for IF to see if you have developed an additional autoimmmune condition (bearing in mind the unreliable nature of this test).

But it's also worth noting that there are many other causes of B12 deficiency (Coeliac disease, Crohn's disease, IBS, gastrointestinal surgery, medications that impede the absorption of B12, infections with heliobactor pylori (gastric bacterial infection)...and many others.

Low folate and vitamin D could be indicative of an absorption problem, in which case B12 absorption may be affected too. If you do have absorption problems, then your B12 level is likely to fall over time.

Note: Treatment for folate deficiency should not be commenced in the presence of B12 deficiency (or a very low B12 result). If B12 deficiency is suspected, or,in the presence of a low result together with symptoms of B12 deficiency, then treatment with B12 should commence 24 hours prior to treatment with folic acid (to prevent very rare neurolgical complications). Not many GP's are aware of this.

Many GP's say that blood tests are normal, when they're not. It's where the results are in the range can be significant. Hovering at the bottom of the reference range (particularly where B12 is concerned) can be indicative of a developing deficiency and it is possible to have the symptoms of B12 deficiency when results are low in the range (what a GP calls 'normal').

It's also worth noting that folate deficiency has symptoms that are similar to those of B12 deficiency. So...

When you get copies of your blood test results, check where the B12 result is within the reference range. If it's not hovering at the bottom of the reference range, suggest that for now, you continue with the folic acid (and vitamin D) and see if this improves your symptoms. If there is no improvement, then it would be a good idea to approach your GP again and ask for further investigations for possible B12 deficiency.

Testing Methylmelonic acid (MMA) and homocysteine can clarify whether B12 is an issue. If the results are raised this can be indicative of a lack of B12 at a cell level - where it's needed (serum/active B12 only shows how much B12 is in the blood - not how much is actually reaching the cellls and being processed properly). So, worth asking your GP for these tests if there is a lack of clarity following further blood tests (if the folic acid and vitamin D don't bring about a good result).

So, if you continue to have problems and still suspect vitamin B12 deficiency, ask your GP for another serum B12 test (to see if levels are dropping), a full blood count (FBC), MMA and homocysteine, and IF antibodies.

We can help with interpretation of blood results if you want help with understanding your results, when you get your current results. Just pop up a new post with the results and don't forget to include the reference ranges (the two figure in brackets following the actual test result).

Please don't be tempted to take any form of B12 supplements, at this stage. These will skew the result of any future blood tests and make if very difficult to get an accurate diagnosis (and hence appropriate treatment), even if you do have B12 deficiency.

Good luck 👍

Mburland profile image
Mburland in reply to Foggyme

Many thanks for all the info which is really helpful. My B12 (plasma) is 616 (range 200-900) btw! Will keep you posted!

Foggyme profile image
FoggymeAdministrator in reply to Mburland

No problem Mburland. It's unlikely (though not impossible) that B12 deficiency is an issue with a serum B12 level of 616. If this was to fall over time it could be indicative of a developing issue with B12.

Suggest you see if the folic acid and vitamin D do the trick, then return to B12 again if there's no improvement (as per my previous post).

Good luck 👍

Foggyme profile image
FoggymeAdministrator in reply to Mburland

Sorry - can't edit reply. Also wanted to note that serum B12 test only shows how much B12 is in the blood - not how much is being processed and absorbed properly at a cell level. Worth keeping in mind if current supplements don't make a difference 😉

Thanks again!

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