I took a PA test recently (Intrinsic Factor Antibody) and it came back positive. I'm always a little skeptical so I did some more research. I ended up finding the information below from Quest who is the lab that did my test. I had been getting 3 b12 injections per week when I got the tests. I believe I got a false positive test. I'm going to take another test in a couple of weeks once I give the b12 shots a break and see what the test says.
"The IFAB test is a competitive binding immunoassay employing an antibody that is specific to the B12 binding site on intrinsic factor. A high vitamin B12 concentration in the patient’s serum may interfere with the assay and cause a false-positive result. Thus, a patient receiving a vitamin B12 injection 1 to 2 weeks prior to testing may have a false-positive IFAB result. Conversely, a patient with a previously negative IFAB result may have a positive result on a subsequent test if the 2nd sample was collected within 1 to 2 weeks of a vitamin B12 injection. Therefore, we recommend waiting at least 1 week after vitamin B12 injection to collect samples for IFAB testing."
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lownskater52
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It refers to a radioimmunoassay test that was superseded by an ELISA test over 10 years ago. But I wouldn't be surprised some labs still used to old unreliable RIA.
I had the same exact question. My IF antibodies test came back as positive while i was taking a lot of B12 shots! I sent a screenshot to my doctor from the Quest Diagnostic website. The same exact spot that you found. And my doctor's response was, "It would not give a false positive test but a false negative test so this is real "
I want to retest as well. But so far - I haven't been able to wait that long without a b12 shot.
My gut feeling is that I have Intrinsic Factor antibodies based on my reaction to taking folic acid vitamins and based on the fact that my b12 serum levels were within the middle of the range.
Folic acid made my neurological symptoms of b12 deficiency blow up. I have no idea why.
Fbirder is probably right in that IF antibodies probably don't cause a bad reaction to folic acid. The issue is that you are NOT supposed to take folic acid if you are b12 deficient. I will create a new post and post a photo showing what my folic acid vitamin warnings say.
My doc (actually a knowledgeable nurse practitioner) had me not inject for a month before testing IF B12 and Folate. I'm waiting for the IF #, but my B12 was high normal 5 weeks after not injecting. I'm wondering if my B12 is still descending (was very high 5 weeks ago due to deliberate generous injecting). My NP also had me stop using alcohol prior to the retest. I'm really curious about the IF #, maybe Monday. If I have IF, then my PA might be alcohol indeuced.
My IF AB test came back negative. That was after 5 weeks with no alcohol consumption. Does anyone know how long you have to be off b12 injections before testing for b12 to get a baseline reading. It showed at 778 pg/mL but Im worried it's still descending. Does alcohol impair or destroy IF?
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I know a negative IF test result can be inaccurate but can a positive one be false?
