B12 results

I have been very tired in the run up to my injection so the doctor asked me to have a blood test just before my injection was due. I did this on Tuesday & got my injection this morning. The results from the blood test showed my B12 as normal (560 range 200-900). My question is will this be total B12 or active B12? I have heard this term used but not sure what it means but like some information before I go back to see GP. Thanks.

3 Replies

  • B12 is carried in the blood by two different proteins, haptocorrin (HC) and transcobalamin (TC). About 80% is HC-B12 and 20% is TC-B12. Only the TC-B12 can enter the cells, this is called 'active B12'.

    The normal serum B12 test (what you had) measures both types HC-B12 and TC-B12. The active B12 test measures only the TC-B12. But the normal ranges of the two will be different. If the serum B12 test has a range of 200-900 then the active B12 test will have a range of about 40-180.

    It's not worth confusing the doctor about active B12 as, even if she did order it done, it would almost certainly show a 'normal' result.

    What you need to do is ask the GP to treat your symptoms, not your numbers, by giving injections more frequently.

  • Thank you. Very helpful. I just trying to get my argument in order before I see him. I hate the word normal ... it seems to be his standard response.

  • the main point to try and get across is that the fact that you have had B12 shots introduces a factor that means that the normal B12 range really doesn't apply anymore

    might be worth pointing them at the area on the PAS forum that is particularly aimed at medical professionals.


You may also like...