Intrinsic Factor test after injecting B12 for 2 years ???

[Ryaan]

Hi

I’ve been SI B12 for the last 2 years or so. I had an appointment with my new GP. First appointment since my last GP retired and she was quite good but told me to get a blood test done for Intrinsic Factor ???

Is there any point in having this test done as I told her I self inject and know my B12 levels will be very high.

Thank you all.

[Gambit62 Administrator]

whilst the intrinsic factor test is affected by B12 supplementation you don't have to stop for a huge length of time - it depends on the exact assay method - could be as little as 24-48 hours after supplementation.

The risk with doing it too close to an injection is that the injection increases the chances of a false positive - ie the test saying you are positive when you aren't.

However, if you have the test (outside the period above) then there is a high chance that there will be a false negative - 40-60% depending on the assay method. So in these circumstances a negative doesn't rule out PA but a positive gives a very high probability that you do.

Knowing what the cause of a B12 absorption problem can be useful as different causes have different consequences. As long as your new GP is aware that a negative doesn't rule out PA and you aren't injecting too frequently to cover the false positive period (can be up to 2 weeks) may be worth doing.

[Ryaan in reply to Gambit62]

Thankyou Gambit for your reply.

So does a positive mean you have PA and negative mean you don’t have PA ?......confused.

So levels don’t matter with this test as I have very high levels 2000 or 3000 in my last blood test as I inject every 2 weeks.

Please clarify as positive and negative is confusing me and also I’m afraid if the results for IFA test shows I don’t have PA then my GP might stop the injections totally saying why do you inject if you don’t have PA.

What I understand is if the test is done too close to an injection it might show a false “Positive”....and if I don’t inject for about 2 weeks it may show a false “Negative”.......but what does a “Positive” and “Negative” mean.

Thankyou

(sorry for going on about it).

[Gambit62 Administrator in reply to Ryaan]

The test will show false negatives regardless of injection.

in terms of results they often come back in various guises - negative is often called 'normal' and positive can be called abnormal. There may be a range and it will show your result as abnormal if it is above that range.

in terms of interpreting the tests, normally it should be - positive = you have PA, negative = this test was inconclusive.

However, as you had had the test just after an injection, which gives a significant chance of a false positive the interpretation should be - positive = this test is inconclusive, negative = this test is inconclusive (hence the comments about being a waste of money).

If your doctor is like most they won't be aware of the limitations of the test so their interpretation will be positive = you have PA, negative = you don't have PA

Suggest you deal with the doctor withdrawing injections because you got a negative if and when that happens. There are options

[Ryaan in reply to Gambit62]

Ok, thanks for explaining Gambit, now I understand but I still have 1 more question.

Why does having the test done close to an injection I.e just having injected a high dose of B12 in to your body increase the chances of positive (I know you said that can be a “false” positive)..

I see the complications in diagnosing someone correctly.

[Gambit62 Administrator in reply to Ryaan]

the test probably involves mass spectrometry - so if there are other things in your blood that have similar mass it can be difficult to distinguish them - probably that the B12 molecule is easily mistaken for the anti-body in the test.

[trelemorele]

Yes, why not?

Instric factor has nothing to do with your levels or self injecting

She wants to see if you have PA or not. Take it if you're offered a lot of people are denied tests in NHS.

Mine instric factor showed up even after 7 years of 12 weekly injections and top.of the range b12.

[Ryaan in reply to trelemorele]

You mean 1 injection in every 3 months for 7 years or 12 injections in 1 week for 7 years. (I do know people who inject daily or twice daily).

To get an IFA test this time I was very serious about the fact that you don’t even know or haven’t tested as to why I’m not absorbing B12.

That and also showed a diary of my injections, the dates, all the symptoms I had, the symptoms that went away. The return of symptoms before 3 months (in 3rd week after injection) and told her the treatment is wrong and told about NICE guidelines for treatment and I read “Could It Be B12” by Sally something partially so believed what I said as I was stating facts which she admitted she don’t know much about. I was fully backed up.

Also I wasn’t feeling too good as was feeling “shortness of breath” all the time and asked for Folic Acid 5mg which she gave as 400iu was not enough and 2 yrs ago my last GP gave me 5mg and shortness of breath completely went in few weeks and I also said I don’t even know my Iron levels and that could be the cause or contributed together with Folate and causing shortness of breath so I had had enough.

I wasn’t rude but wasn’t too happy and she could tell so agreed to further testing.

My advice to anyone with B12 issues is to research all about B12 and when you go to your GP go armed with this info and GP most likely will take you seriously and forget about the practice guidelines ( my previous GP didn’t care about guidelines) and treat your symptoms and tell them it’s not your favourite pass time or hobby to come to visit them but you come because you’re sick and need treatment.

I also told my last GP who retired (was a nice guy) that you’re not treating me properly and wrote down NICE guidelines for B12 deficiency and neurological symptoms so he put me on weekly injections.

You have to go armed like John Rambo or you lose the battle.

😀

Thanks for your reply.

Sorry about my long reply.

[trelemorele in reply to trelemorele]

One injection every three months for seven years. Why are you in combative mode, I'm trying to give you answer based on my own experience to hopefully help you and others with similar query.

PA will show as instric factor positive on you blood results.

Now, apparently for some people PA doesn't show up or the test itself is inaccurate. So you may have 50/50 chance I understand.

Anyway, I'm the example testing time doesn't matter even if you have regular injections and have high b12 levels.

Take this information or leave it.

[Ryaan in reply to trelemorele]

But I liked your answer. I’m not in combatative mode. I appreciate you taking time out to help me (and has helped me to understand), and hopefully others too.

The John Rambo bit was a joke.

Thankyou for your help, sorry for any misunderstanding.