ACTIVE B12

[Diana49]

Hi, can someone tell me what are the optimum levels of ACTIVE B12 please?

[wedgewood]

The range for the Active B12 test readings are from 37.5 to 187.5 pmol/L

My old serum readings were always right off the scale .( I inject every week) Now my Active B12 reading is within normal limits at 150 pmol/L

Which I think proves that the old blood serum reading did indeed contain inactive B12

Best wishes.

[FlipperTD in reply to wedgewood]

The 'old blood serum reading' was [and is] measuring total serum B12. This includes the B12 bound to all of the transcobalamin proteins. Transcobalamin I [Haptocorrin] and Transcobalamin II are present in proportions of about 75% Transcobalamin I to 25% Transcobalamin II. Before B12 is measured by the traditional methods, it's necessary to separate the B12 from the binders. As a consequence, the serum B12 assay measures the lot.

It would, of course, measure any free [unbound] B12 in the serum too. If you're actively replacing B12 by injection, then measuring serum B12 probably isn't that useful.

[wedgewood in reply to FlipperTD]

Thank you FlipperTD 👍

[wedgewood in reply to FlipperTD]

Very recently , my GP had my blood tested ( nothing to do with P.A. ) and my B12( blood serum) reading was off the scale . My private blood test , which I have annually , was done 2 days later . The B12 readings - two results ( one blood serum , the other Active B12 ) were remarkable regarding the different results . Serum off the scale , Active within range . But most NHS GPs say that NHS will not do the Active test

. When I had untreated P.A. , a few years ago , my serum B12 was below range ,and I was sent on my way . Everything normal , no action — ( didn’t know then that I could have asked for a print -out , and I trusted my previous doctor. — ) . I am now paying for that neglect with irreversible problems .

Sorry to go on so . But I’m overwhelmed sometimes .

[FlipperTD in reply to wedgewood]

Don't fret! I don't mind in the least.

If you're on regular B12 treatment then it will be off the scale, or it could easily be. We simply don't know. If some is free B12 then that's just on its way via your bloodstream, through your kidneys, and thence to the drains! So the big number is meaningless. Your active result is far more meaningful, but frankly if you're on regular B12 then it's really not worth wasting the assay. The NHS doesn't normally do the Active test as it's a completely different method and equipment, more expense and doesn't add much value. It would be an extra test, not an alternative. I suspect some NHS labs may run it, but some of that could be down to 'Income Generation'! If 'Big Hospital A' can get enough work referred in then it's worth doing it financially, even if it's not adding a huge amount to clinical care. My laboratory 'did very nicely' out of IFAb tests, as we were one of a few that did them, and could justify running the test 'live' because we had enough requests. Somewhere with only a few might not get enough requests in a month to make it viable. We 'did nicely' out of Erythropoietin too. The folks in the lab didn't benefit; the income earned was for our hospital. There's a huge network of labs providing referral services. Requests referred in are done, and billed out for the cost. The 'off the scale' was measuring the B12 bound to TC I and TC II, and also any free B12 in your serum at the time.

You were let down.

[ratnababu in reply to FlipperTD]

In the U.S, I can't even find a private lab that does HOLO TC / Active B12 tests.

[FlipperTD in reply to ratnababu]

That doesn't surprise me at all. I don't know if the test has jumped through all the hoops placed by the FDA so it can be sold in the US, or even if the manufacturers who make the test even attempt to sell it into the US, to be honest.

The market for these things if more complicated than you'd guess. In some ways I find that quite reassuring! [That's just kicked the hornet's nest.]

The complexity of adding yet another analyte to a lab profile can be surprisingly tedious.

[FlipperTD in reply to wedgewood]

It's worth mentioning that these tests were done in different labs. Measuring B12 isn't straightforward, and although the tests are very precise [same answer again and again on the same sample] testing it in another lab may well give a different answer. That's why we provide reference ranges. If the result is 'over-range' than that just means 'big number'. To put a number on it would require the sample to be diluted and repeated, and that increases the cost. You don't need to know quite how much 'a lot' actually is. If you're injecting B12 then you could measure every hour, and get varying results. That's nothing to do with the test, and everything to do with physiology.

[wedgewood in reply to FlipperTD]

Thanks again Flipper TD . It’s really good to have someone onboard who really understands the science .👍

[Asselchen]

Optimal is >70/>75 pmol/l (depending on who you ask).

[Gambit62 Administrator]

there is a lot of variation with B12 - and different people will be okay at different points - some will even be okay below the normal range and others won't be okay until they are actually over the top of the range. As such I feel really uncomfortable about people trying to apply an 'optimal' point to it.

What is optimal for individuals can also change significantly depending on treatment, though I suspect that the variation on active B12 may be less responsive to treatment

[wedgewood in reply to Gambit62]

That’s useful Gambit 62 . If only GPs would realise that fact , life for P.A. patients would be quite different . We are powerless until doctors realise the facts about P.A. Until that happens , we struggle on . Thank goodness for our forum and members like you.