"Normal b12 level"

Reference ranges aside, does anyone know of any studies that have shown what a normal b12 level looks like?

Reference ranges I guess are made up from averaging b12 results from all tests done on people who were not referred to the lab with symptoms.

Also does anyone know how long it takes the liver to 'fill back up again' once the levels have become depleated.

I got my levels up to around 900pg using sublingual hydroxycobalamin but missing one days has a definite effect on how I feel. (Blood tests done while still supplimenting, tested before supplimenting on the day).

Wouldn't stored b12 come into play on any days you missed supplements? Surely that's why they leave weeks between injections or does the injected b12 stay in the muscle/fat rather than being stored in the liver?

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  • if you have an absorption problem then the liver won't 'fill back up again' - which is why you need B12 injections for life. In someone who doesn't have an absorption problem B12 is stored in the liver and then released into the ileum in bile for reabsorption as necessary. However, if you have an absorption problem then the reabsorption from the release in bile also isn't working - it's like having a whole in a bucket that empties faster than it is getting topped up.

  • So how does an injection last three months but sublinguals need to be taken daily yet effect blood results for weeks.

    If ever there was a case for totally ignoring blood b12 results.

    It's terribly confusing

  • when you have a B12 injection nearly all of that ends up going into your blood and it then stays there until it is either used or gets filtered out by kidneys and passes out of the body in urine.

    although you are taking a lot into your body via your mouth with a sublingual very little of that actually gets into your blood (if you have an absorption problem) - most of it just passes straight through the gut. In general you end up needing several hundred if not thousand times the amount of B12 orally that you would need by an injection - so effectively all you are doing is continually topping up the levels in your blood a little bit each time you use a sublingual - rather than putting a huge amount into your blood in one go.

  • So would you say that I don't have an absorption problem if I've been able to get my serum b12 up to 900 pg on sublinguals?

    That was on methyl b12 with a weeks break before the test.

    I'm using hydroxycobalamin sublingual now and my last reading was 703pg while still supplimenting.

    Before supplimenting my serum was 153pg

  • No, I am not saying that you don't have an absorption problem - far from it - if you didn't then I would have expected the levels you are taking orally to have raised your levels much higher.

    however, having an absorption problem doesn't mean that nothing gets absorbed - just that the amount that gets absorbed is very significantly reduced (a few % if that of normal).

  • What about B12 patches? Do they go straight into your bloodstream?

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