High active b12 result

Hi all,

Active b12 test question:

I just got an active b12 result of 234 and the range is 25-165. I've taken b12 supplements sporadically over the past few years. I had been off them but took a few days worth this week. It was a test I not been planning to take and I know now it might have been altered by the supplements. My question is, could it have been altered by that much? To me, the number seems alarmingly high. I'm a 29 year old with CBC,renal and liver panels all done a year ago and all within healthy ranges. No symptoms, just confused!

19 Replies

  • What does your doctor say? My doctor just prescribed me b12 injections and my blood b12 isn't low. She feels we need much more then recommended, and figures it will help with low energy, but now I wonder if I need a 2nd opinion.

  • Your doctor is correct. Google it if you like.

  • An Active B12 blood test isn't the same as the B12 test we have in the surgery.


  • I had the same (>256) even though I hadn't taken any supplements for months.

    With me it looks like the reason behind it is because I have a mutated MTHFR gene so I can't get rid of it from out of my system.

    Still working on the answer.

  • You don't really need to worry about taking too much B12 as the body just gets rid of what it doesn't use in the urine.

    In a normal B12 test you can start to experience neurological alterations in levels under 500 so best to be above that.

    I'm not sure about the active B12 test but I have read that excess B12 in the blood is unusual and can indicate liver or kidney disease but as you had yours tested and all came back fine I doubt this is the case. Talk to your GP and get a second test as you can get false positives and false negatives. Maybe your supplements just before test have altered it.



  • If your active B12 is high and your serum B12 is high then you don't need to supplement B12. If you still feel bad maybe your folate level is too low. However the best people to discuss this with are the pernious anaemia society who are on healthunlocked. So I would join that group and ask them sharing all your blood test results.

  • Yes, my bruising for no apparent reasons has now stopped - once I took B12 supplements.

  • Oh wow! I used to bruise very badly...but recently fell getting out of the bath on my ribs...only the tiniest of bruises whereas before it would have been much worse. I didn't know that it was related to B12...like so many other things.

  • Hi Flower girl,

    As per the TSH test the 'normal ranges' for B12 are based on bad science and poor understanding. B12 is an anti-oxidant so higher levels may actually be beneficial. My Doctor considers twice the normal range to be a minimum.

    When you have these tests done you should not be taking supplements for 24 hours before or that can skew the results.

  • have you been symptomatic of B12 deficiency.

    If not my advice would be not to supplement.

    Both serum B12 and to a lesser extent active B12 tests are difficult to assess and trying to use them as single markers is at best difficult. The normal range for serum B12 is set such that 25% of people will be deficient in the normal range and 5-10% will be okay even below the bottom of the range - symptoms are what really counts - though I recognise that the huge overlap with other conditions, including thyroid, makes this difficult to assess.

    if you need any more information then suggest that you look at the PASoc site which is very much focused on B12 as B12 deficiency is the key factor in causing the symptoms of Pernicious Anaemia


    There is no known toxicity from B12 and one form is used as the treatment of choice for cyanide poisoning because of this - and is administered in doses that would be at least 5000x the amount you have been taking

  • Thank you! I've responded to everyone below but thank you for the PA reference. I haven't been symptomatic lately and hadn't had my serum tested in years, since I came up deficient 5 years ago, and had not ever taken an Active test. My family GP just said, well okay, it looks like you're absorbing now! (Since following a gluten free diet), so be happy! and stop the supplements haha

  • coeliacs can cause B12 deficiency because of the effect that gluten has on the gut so may be that going gluten free was the answer to resolving the absorption problem for you.

  • Mine was similar because of supplements. The consultant said that "normal" results weren't correct with thyroid sufferers as we just can't digest it. Hence we need a lot more. So shows as way above "norm" but isn't really. In his opinion, the more B12 we have in our system the better, so that at least some of it gets absorbed. Hope that eases your mind? It did mind. 😘

  • An Active B12 blood test is not the same as the one we have in the doctor's surgery.

    If you've been supplement a few days before I should think the results will be skewed. I'm not medically qualified but you should check on the P.A. HU site.

  • You seemingly can't overdose on b12 I wouldn't worry some say take it till your pee turns pink and then you know you reached optimal , mine is 400 I take it every day

  • Thank you all! I just posted in the PA society. I really do hope that the Active B12 was high due to my supplements. I had taken one just 48 hours before. I used to be deficient, according to past serum tests. My family GP just said, well! We can look at your full serum test but for now stop supplementing and be happy your body is absorbing B12 into the Active form! Hoping she's right. I have ZERO symptoms anymore which is the weird thing. I was diagnosed Celiac with a bit of an under active thyroid years ago but since following an elmination diet and losing weight, my symptoms have subsided.

  • Congratulations on the results from your change in diet. Sounds to me like you are doing well!

  • Hi,

    I have had a very high b12 level for the last 3 years, possibly longer but only been tested regularly for last three years since hashis diagnosis, my levels are regularly 1200 PLUS where the top of the range is 800. I have never supplemented but have all the symptoms of b12 DEFICIENCY!

    Have had tests for numerous things at hospital but no problems identified, seems some people just have abnormally high levels without anything being wrong. Hope that helps!

  • Hi mine is the same I'm coeliac and hypothyroid take thyroxine . My B12 was over 2000 really worried when the GP said it could be the sign of something sinister going on 😫 I used to have injections but haven't had one for over 2 years now !

    No other tests undertaken just said we will keep a eye on it ? Xx

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