There are two different ways of stating the results from these tests (well more than two, but let's keep it simple).
The old fashioned way described the mass of a chemical found in a volume of blood. So your original result for B12 was 119 ng (billionths of a gram) in every litre of blood.
Medics are moving to the modern way of describing concentrations which uses the number of molecules found in a volume of blood. But, if the used the actual number it would be confusing. Instead they use the chemists's concept of a mole.
A mole is just shorthand for an amount. Just like a dozen is 12 of something, a score is 20 of something, and a gross is 144 of something. A mole is 602,000,000,000,000,000,000,000 of something. (That number was chosen so that a mole of hydrogen atoms weighed one gram).
So your second reading of 352 pmol/L means that you had 352 trillionths of a mole of B12 molecules in every litre of your blood.
Obviously, the bigger and heavier the molecule the more mass you'll have per mole. You do the conversion using the molecular weight (I bet you thought you'd finished with that years ago.
Hydroxocobalamin has a molecular weight of 1347 grams per mole. To convert from ng/L to pmol/L you divide by 1.347 so your 119 ng/L equals 88 pmol/L
But the two results would have used different tests, which would have different normal ranges. The best way to tell if you've improved is to compare your result with the bottom of the range.
Your serum B12 is close to the bottom in both tests. What is strange is that your Active B12 is very high. Normally you expect the Active B12 to be about one-quarter the serum B12. But yours is one-third.
Thank you so much fbirder, I really appreciate your detailed reply! Am I correct in thinking that it’s likely I don’t have PA as I tested negative for the intrinsic factor and I am absorbing from supplements? Indeed my first B12 test was under range and after three weeks supplementing it is within range (albeit still low in range)?
Intrinsic Factor Antibody tests are problematic. There are numerous methods, and different types of antibodies 'out there' to detect. Consequently there's no one simple test that can be done. If it's positive, it's diagnostic. However, in around 50% of PA cases, it's negative.
The best test we had was the Schilling Test, but that's not been available for a long time. It used a radioisotopic Vitamin B12 tracer, and Pig Intrinsic Factor, and involved a 24 hour urine collection. The process was expensive and labour intensive too, but has a good test for diagnostic purposes (usually) although it could still have problems.
If you're absorbing oral B12 supplements it sounds like you don't have PA, although 'opinion is divided on the matter'!
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Blood test results
New to all this, please help with test results
Help with blood test results
My blood test results
