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Homocysteine and Anti-parietal cell antibody tests if supplementing with Folic acid

AidaA
AidaA

Yesterday I took 5mg of folic acid and the day before, 4mg and I have to test anti-parietal cell ab and homocysteine. How long should I wait? Is one week enough or not, so I don't get false results? Thank you.

13 Replies
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Hello, I am sure someone will be along soon to give you a more comprehensive reply but in the meantime I did find this interesting link labtestsonline.org/understa... Are you currently getting B12 injections? This link suggests that having a B12 injection within 48 hours or up to 2 weeks before testing intrinsic factor antibodies can interfere with test results. As for the folic acid, I am curious about the answer to that as well.

AidaA
AidaA in reply to Cobalamin4Life

Hi. Not yet, the hematologist said I could start the injections right after I do these tests, but forgot to tell her about the 9mg of folic acid.Ugh.

I have to test anti-parietal cell ab and homocysteine, not intrinsic factor antibodies. The results came back negative for IFA (2.3 U/ml and it should be <6).

Gambit62
Gambit62Administrator

in respect of B12 implications for the results supplementing with folate shouldn't make a difference but check with the lab/whoever is doing the test.

Homocysteine can be raised by folate deficiency so is a bit problematic as a way of diagnosing B12 deficiency if you also have a folate deficiency - MMA would be a better test as this isn't affected by folate.

AidaA
AidaA in reply to Gambit62

I'm on the lower end of range on folate. From my understanding, homocysteine is affected by the supplementation of folic acid, but I don't know for how long with my 9mg...

I know about the MMA, but this is what the hematologist said I should do and I just want it done so I can begin injecting already.

fbirder
fbirder in reply to AidaA

Folate has a fairly short half life, so I would think that Most of that 9 mg would be gone a week later.

However, if the hCys test was looking for a folate deficiency it may be that the high levels of folate you would have had for a few days might have been enough to reduce hCys levels.

Bottom line: a low hCys result will not tell you much, except that B12 probably isn't a problem.

AidaA
AidaA in reply to fbirder

Thank you! I have a diagnosis of b12 deficiency, my b12 is at 153 pg/ml, but I would have liked to know for sure if I have PA or not. I think I'm going to skip on these two tests after all...

Gambit62
Gambit62Administrator in reply to AidaA

IFA is the test for PA as a cause of a B12 deficiency - homocysteine isn't a test for PA its a test for B12 deficiency/folate deficiency which could have been caused by any number of things including and most probably PA.

IFA is prone to false negatives 40-69% of time depending on assay method - so a negative result is a long way from proving that you don't have PA and that isn't the test which would be affected by folate supplementation.

AidaA
AidaA in reply to Gambit62

I wanted to do them because my doctor told me, so to please her basically. I did the IFA test without anyone telling me to and it came back negative (2.3 U/ml and it should be <6). Is there anything else I could/should do to see if I have PA?

Gambit62
Gambit62Administrator in reply to AidaA

you can try repeating the test but no guarantee that it won't be giving false negatives.

There is some research to show that gastrin levels could provide a much better test for PA but don't think this is officially established at the moment. They tend to be extremely high in someone who has PA

AidaA
AidaA in reply to Gambit62

Thank you!

fbirder
fbirder in reply to Gambit62

Gastrin levels will be high in people with low stomach acid, which is common In those with PA. But there are some other possible causes, like Type 2 gastric NETs.

But, yes, high gastrin in combination with low B12 would be a good indicator of PA.

AidaA
AidaA in reply to fbirder

I for sure have low stomach acid because I was diagnosed with chronic gastritis+Helicobacter p. 1 month ago. Also with Hashimoto, so who knows what caused what.

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