I am supplementing 5mg of methyl b12 sublingual daily. Will this affect the results if an intrinsic factor test? I decided to supplement myself after having low normal b12 238. Since supplementing the numbness and tingling has improved greatly. However I am still very off balance when walking. Any advice in what I should say to the Dr as he believed my b12 was ok. Surely the improvement since supplementing proves otherwise...
Thank you in advance.
Hi Awil a wiser person than I has commented previously "For testing intrinsic factor antibodies: keep one week between an injection and the test".
I am not a medically trained person.
Thank you for your response. I have looked at the PAS symptom list and I have or have had 15 of them in the last 3 months. Although not diagnosed with coeliacs I am sensitive to gluten and have recently stopped eating it. Do you think it's likely I could have pernicious anemia?
The symptoms of PA are the symptoms of the B12 deficiency that it causes. If the cause isn't dietary then it is an absorption problem so you need to find another way of replenishing B12 initially. Most absorption problems aren't treatable but a few are - notably h pylori infection - which would mean that once that has been dealt with you would be able to absorb B12 from your diet so wouldn't need maintenance shots for life.
The Intrinsic Factor Antibody (IFA) test is unreliable in that it gives false negatives in people with PA half the time. So a negative result doesn't mean that you don't have PA. However, a positive result is a sure-fire, 95% certain indicator of PA.
Please remember I am not medically trained but have had P.A for more than 46 years.
Intrinsic Factor test result
Positive intrinsic factor tests
Intrinsic factor antibody 
Intrinsic Factor at top of range
positive then negative intrinsic factor 
