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

[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.

[Cobalamin4Life]

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 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 Administrator]

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 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 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 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 Administrator 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 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 Administrator 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 in reply to Gambit62]

Thank you!

[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 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.