Okay, so we already know that the IFA test is only 50% reliable. That means it will only pick up 50% of people who have the antibodies. Anybody else can go jump in a lake.
Now we have this:
"Do not order intrinsic factor blocking antibody (IFBA) testing in patients who have received a vitamin B12 injection within the last 2 weeks. High free serum vitamin B12 levels, as may be seen within the first 2 weeks after a vitamin B12 injection, can interfere in the IFBA assay, leading to false-positive results. We reflex all positive IFBA tests that have not been ordered through the Pernicious Anemia Cascade to vitamin B12 measurement. If this yields a level >800 ng/L, we append a comment to the report indicating a possible false-positive result.
Some patients with other autoimmune diseases may have positive IFBA assays without suffering from pernicious anemia (PA). This is reported inparticular in patients with autoimmune thyroid disease or type I diabetes mellitus. In the validation of this assay, "
This means that anyone who had a B12 injection within the 2 weeks before having an IFA test most likely gave a false positive result. ie They do not have PA. It also says the same stands for people who have autoimmune thyroid.
So trying to sort this mess out (and I'm excluding here the mess associated with parietal cell antibodies) we have a situation where they are using a test which is only 50% accurate, can throw up a false positive result in the remaining 50% if they had B12 for the 2 weeks prior to the test, or they have autoimmune thyroid or type 1 diabetes.
This, of course, is based on the assumption that they are chasing the right thing - ie an anaemia - which has been proved not to be the case - and that low B12 don't really matter....
And, of course, this is now all occuring because for some strange reason it has been decided that B12 deficiency is only important if it can be diagnosed as an auto immune condition - whereas the biochemistry states that it is the lack of b12, for whatever reason, which causes neurological and psychological damage.
How sad that we rely on such unreliable science instead of physical evidence from the patients.