I know a negative IF test result can be inaccurate but can a positive one be false?

[Tinglypalps]

I've not been well since the middle of 2020, nothing to really put your finger on but headaches, tiredness, feeling like you're coming down with something but in December 2020 I started having episodes of palpitations. Was sent to A&E a few times but obviously by the time they got to ECG nothing was wrong. In the past two months I am now getting achy weak arms and at night while sleeping (flat on back so not squashing anything) dead and tingly hands. It wakes me and I have to massage them back to life but it tingles afterwards for days. I'm only 39 by the way and never had any health issues at all, although family members are riddled with auto immune diseases of diabetes, lupus, ulcerative colitis, thyroid issues etc.

GP sent me off for full bloods to his credit, and included tests for 4 antibodies as well which all came back negative, including the parietal cell autoantibody level. B12 results were - serum holotranscobalamin concentration of 94 pmol but the lab had put a comment on the result to say consider a empirical trial of B12 treatment or follow up laboratory testing. (No idea why but I could see this when I logged into the patient online part of the website to view my results prior to my GP apt.) This got me googling B12 issues and I had so many of the symptoms of a deficiency it was untrue. I got to the drs apt last Tuesday to be told everything came back normal and that was that. I therefore paid privately for an extended B12 test as I couldn't shake the feeling B12 was key and these results have come back today stating that my active B12 levels are too high at 176 pmol (normal range is 25.1-165) and that I have tested positive for Intrinsic Factor antibodies.

My question is - can I have a problem with IF and B12 if I have too much B12 in my blood not too little? And while I know that there are false negative IF antibody tests - is it possible that a positive one can be false or am I looking at getting on to the drs here and annoying them with my private test results?

Thanks so much for any responses! This is a bit new to me!

[Nackapan]

I've heard it's possible to have a false positive Intrinsic antibody test if serum b12 levels are very high.

Usually when on b12 Injections.

Have you been on oral b12 supplement?

If not you need further tests to see what's going on .

Get z ptibg out of born sets of blood tests for your own records

[Tinglypalps in reply to Nackapan]

No I've never taken any supplements at all so no idea why its too high! I've sent the results over to the drs to see if they will do something with them like retest but wasn't sure they'd take them too seriously as i had arranged them myself! Didn't know whether the IF antibodies mean its a definite PA for me or not!

[Nackapan in reply to Tinglypalps]

I imagine it is .I woukd now try snd get some answers

Nevers ends does it

[Cherylclaire Forum Support]

A problem with connection ? Thinking that perhaps it would be useful to know whether your methylmalonic acid (MMA) is also building up in bloodstream. That it could be functional B12 deficiency: your MMA and B12 are not linking together and moving on to cell/tissue level. So symptoms remain/ worsen.

This is only a possibility - but would require elimination of other causes for raised MMA -like renal function problems or small intestine bacterial overgrowth. An MMA test can be difficult - local hospitals unlikely to do it - but not impossible for a GP to get requested. My GP got refused twice before she found a hospital who would test.

[NJPoet]

From what I gather, it also depends on the type of test kit the lab uses. For example, Labcorp in the States informed me that the test they use would not be affected by B12 levels in the blood. At least, that’s what they told me.