Help with B12 levels and maintenance dose please.

My B12 levels were 198pg/ml so I started supplementing with 5000mcg daily. Next test showed levels had risen to 2000pg/ml so I cut back to 5000mcg once a week. Next test showed levels at 799pg/ml, which I understand is about right, so I continued at the same dose.

3 months later I notice that the aches and pains which had definitely improved, are now back with a vengeance, so it looks as though my levels are sliding downwards again.

How do you work out what is an adequate maintenance dose without getting tested every month? GP won't test again.

10 Replies

  • B12 is a difficult one to test once you are treating. The result shows what is circulating in the blood - both bound and unbound - so once taking high doses it will be reflected in the result. The test itself is only a snapshot and of course the ranges seem inadequate. Only 20% of the test result is available at a cellular level where it is needed. In Japan the range is 500 - 1300 - which is interesting ! Having the more reliable ACTIVE B12 Test done privately would mean coming off the B12 for at least a month I believe.

    The above link is about a strong B12 that is the same as the injections. Also you could try B12 Hi-Strength patches from amazon as they also include the other B's and Folic Acid. B12 needs to be taken with folic acid - they work together. The patches contain 5000mcg B12 and are popped on weekly...

    How are your VitD levels - as low levels can sometimes be the cause of aches and pains....

  • Thanks Marz - that's interesting. I did have the active B12 test done last year and I was over their reference range...but I didn't know about leaving off the supplement for a month (I left it off for just a couple of weeks), so clearly there was still masses swooshing around in my blood.

    I'm in the same position with VitD levels - i.e. they were way up high, so I cut back and they dropped too low again. I'm now in the process of building them up.

  • I'm not an expert and have only learned from others here. Hampster1 for one ! Maybe check out her posts - they are so informative. Think she is away at the moment....

  • Thanks - will do.

  • I was seeing Dr Skinner and he recommended that anybody with thyroid problems should take 1000mcg B12 daily.

  • Thanks debjs - once I've finished this bottle of 5000mcg I'll try what you suggest.

  • Hi Sue-F, I have PA I inject 1,000mcg twice a week and take 5,000mcg sublingually most days. You need a continued level of 1,000 in your blood to repair any damage low B12 has done to you. If people aren't absorbing B12 from their food, levels can drop drastically if you cut down. B12 isn't toxic, and I know of people who inject 1,000mcg a day in order to stay well.

    Did you get your folate HB and ferritin levels checked?, I'm sure they are bound to be low. You should ideally have a folate result of around 12.5 to utilise the B12 you're taking, and ferritn at least 80. Usually if you're low in B12 you're low in iron. If your folate was very low your doctor should prescribe 5mg a day for around 4 months.

  • Thanks Helcaster - last ferritin test came out at 110ug/L, so that seems OK, as is folate at 12.2

  • Hi Sue, as the others have said, it is pretty useless to test B12, even an active B12 test, when you are already supplementing. My GP was under the impression that you should take B12 until you were in range which is completely wrong.Luckely I have found another one. I am still doing my loading dose injectiones every other day and slowly improving. Oral supplementation had very little effect. Your levels are low and I am supprised that you have not been offered injections.


  • Thanks Roslin - this is clearly even more complicated than I thought.

You may also like...