Low B12 (plus recently medicated for underactive thyroid)

[Tired_MiddleAged]

Hello all

I’ve had some private bloods done to aid thyroid investigation with my GP (a whole other thread!). I really had to push the GP to listen to me so have lost some confidence with them. The GP didn’t pick up on this low B12 result.

Anyway my B12 results are 29 pmol/L and ref range is 37.5 - 188. I’ve felt dreadful for so long.

Someone on the Thyroid thread recommended seeking advice on this thread, as once again I feel like I am going to have a battle to get my GP to help me with this. Just want to feel normal!

Any advice welcome! Thanks

[jade_s]

Hi I've been following your other post and agree with their suggestion to first get a hold of the old test(s) and reschedule a new draw ASAP. I would also ask them to test intrinsic factor and gastric parietal cell antibodies.

Do not take any b12 yet or any B complex, energy drinks, or similar. The blood test can end up showing normal when you're actually deficient.

I have to run now but i'll post more when back and others will likely be along with more resources.

Is this an Active B12 test?

[Tired_MiddleAged in reply to jade_s]

Thanks Jade! Will hold on taking anything yet. And I’ve just requested the January bloods so I have that compared to the recent bloods I had with medicheck.

Presume I would need the Dr to agree to a new NHS blood test though? So will book an apt once I have both sets of blood results.

[jade_s in reply to Tired_MiddleAged]

Hi Tired, yes I guess you would need to get Dr to agree to NHS tests. I am not in the UK myself but I am sure others can help you formulate an argument. I have heard that they don't usually accept private tests but I think you could argue that since your January levels were trending low, you really would like to check your current status. I don't think you need to wait for your old results to book a new test. Your active B12 is very low as is, and I wouldn't delay.

In the meantime you can read about pernicious anemia in the many resources provided by Sleepybunny, see for example healthunlocked.com/pasoc/po...

In a normal person, intrinsic factor (IF) is a substance made by your stomach, and it allows your body to absorb B12 from food, tablets, and so on. It transports B12 from your intestine to your bloodstream. B12 is a large molecule so it requires these "transporters" to go from one place to another within the body.

In people with the disease called "pernicious anemia" (PA), the body makes antibodies against IF. This can be tested via the Anti-intrinsic Factor Antibody Test, abbreviated IFAB. This is often called the "pernicious anemia test" because these antibodies occur only in pernicious anemia. Gastric parietal cell (GPC) antibodies are also useful to get. GPCs are the cells in your stomach that secrete stomach acid and IF. However GPC antibodies can be raised due to other conditions, so most doctors do not consider them diagnostic specifically for PA. Still, you should push for both antibodies. However in up to 50% of people with PA, the antibodies will come back negative. It's a bit like a covid swab test - if it comes back positive, it's diagnostic. If it comes back negative - you could still have it.

There are other tests for low B12, such serum B12, active B12, homocysteine, and MMA. But these are not specific to pernicious anemia, because there are many other causes of low B12. But that doesn't matter, in someone with suspected B12 deficiency / B12 malabsorption / pernicious anemia, these test are also helpful in diagnosing a deficiency.

*However* these tests may be falsely distorted if you supplement B12 or get an injection before you get a blood test. That is, the tests may say "no you don't have B12 deficiency" when in fact you do. It can take many months for B12 levels to fall back down to low levels. That's why people recommend getting testing first, and then supplementing.

[Tired_MiddleAged in reply to jade_s]

Thank you Jade this is really interesting. Calling the GP later. Thank you for taking the time to respond.

[jade_s in reply to Tired_MiddleAged]

You're very welcome. Let us know how you get on with the GP.