Useful podcast from Chris Kresser recently about B12 being under-diagnosed. I am being asked about the holotranscobalamin II, or holoTC form of B12 which detects early stage problems, which is why I was looking at it.
I realised I have been a daftie recently because people have been asking me if I can get the holoTC form tested and I’ve said no. I realised today that the active B12 test I have been offering all along is, of course the holotranscobalamin II test! Doh!
First, here is a taste of what Chris was saying but do read the whole transcript.
Why B12 Deficiency Is Significantly Underdiagnosed
There are more sensitive markers for B12 deficiency that are now available including methylmalonic acid (MMA), which can be measured both in the serum or the urine. And not so much in the US but in Europe and other parts of the world, there’s another marker called holotranscobalamin II, or holoTC. That’s in fact the most sensitive marker for B12 deficiency. It is capable of detecting B12 deficiency at the earliest stage, stage one. These markers are much more sensitive to B12 deficiency than serum B12, which means they’ll go out of range at an earlier stage of B12 deficiency.
Then we also have homocysteine, which is a marker of B12 deficiency, although it’s not exclusively related to B12. Homocysteine can be high in cases of folate deficiency or even B6 deficiency as well. Homocysteine is more sensitive than serum B12, but it doesn’t only reflect B12 deficiency. If you see it high, that tells you that either B12, folate, or B6 is low, and you need to do some additional testing with these other markers to determine whether the cause of the elevated homocysteine is related to B12 or if it’s related to folate or B6.
Those are the additional markers you can use. Serum B12 is still a useful test and can still detect deficiency in some patients, but those people are people that are in stage three or four of 12 deficiency. There are four stages: One, two, three, and four—and serum B12 doesn’t typically go out of range until stage three or four, so you’re missing people in stage one or two if that’s the only marker that’s used. Homocysteine and methylmalonic acid can detect people in stage two deficiency. Holotranscobalamin or holoTC is the only marker, unfortunately, that they can detect people in stage one deficiency. It’s a mystery to me why it’s not available in the US.
And here you can read much more about the MMA and Active B12 test that Biolab does for me. This measures the stages 1 and 2 as above. HoloTC also in the full TDL anaemia test. You can get both of those here in the Nutrient tests section.
You can also see some of my other witterings on B12 here: