THE VITAMIN B12 AND FOLATE PATHOLOGY INVESTIGATION
THE INVESTIGATION OF ERRORS IN PATHOLOGY TESTS
FOR VITAMIN B12 AND FOLATE DEFICIENCY
BY MEANS OF MEDICAL EXPERIMENTS
B12 AND FOLATE INFORMATION
B12 NOTES
Serum B12
Monitoring Treatment
Tests
Treatment
Sources of Information

You can use serum B12 to assess the effectiveness of treatment, as distinct from diagnosis, to some extent. Your serum B12 level represents the body storage of B12, if they are in equilibrium. I shall explain what I mean by this.

If you are taking B12 supplements, then suddenly stop, the B12 in your serum decays exponentially. The rate of decay, called the half-life, is the time it would take for the amount of B12 to reduce to half of the original. For serum vitamin B12, the half life has been found to be about 10 days. This means that, if you had B12 in only your blood, and none in body stores, it would take 10 days to fall from the initial level to half of that. Because you will have some body stores, the rate of fall is more complex than that.

An example of this is shown in this chart:

Chart C10

You can view a larger copy of the chart by selecting the blue link above the chart.

This chart shows how my serum B12 increased from 100 pmol/L to 1232 pmol/L after taking two 1000 µg B12 for 100 days. The serum B12 level fell to 1099 pmol/L, possibly because of instability when it was no longer in equilibrium with body stores. After I ceased all treatment, my serum B12 level fell to 660 pmol/L in one week, to 601 pmol/L after two weeks, and to 323 pmol/L after a total of five weeks. My serum B12 level then gradually fell to 140 pmol/L over the next few months.

The initial serum B12 level, of 1099 pmol/L, was affected by recent absorption of the supplement, and did not truly represent body stores. It took five weeks for the serum B12 to come into equilibrium with what was in my liver.

Here is another point about the chart. At what point, on that chart, do you think that I became B12 deficient? The answer is that you cannot tell. According to my interpretation of MMA results, cellular deficiency commenced within three weeks of my B12 level falling to 323 pmol/L, at about Day #140. It is impossible to see that from the B12 chart.

So, you can use serum B12 as a guide to changes in your body stores, but not cellular deficiency, and only if you wait for several weeks after ceasing supplements.

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