MMA test?

[jillc39]

the haematologist I saw asked for an MMA test - gp wouldn't do it, so he arranged it for me. Anybody know what it is for, and what it might show?

[Sleepybunny]

useful links

b12deficiency.info/b12-test...

labtestsonline.org.uk/under...

[Gambit62 Administrator]

MMA is a waste product that builds up if you don't have enough B12 available at the cell level. B12 deficiency isn't the only think that can cause levels to be elevated which is why it isn't a normal test for a B12 deficiency

[jillc39 in reply to Gambit62]

thank you both for the speedy replies.

[fbirder]

One of the things that B12 does is to help convert methylmalonic acid (MMA) into succinic acid. If there isn't enough B12 then the conversion process isn't efficient and the amount of MMA builds up.

A test for MMA will show if your B12 is working properly. For those with a B12 deficiency it's about 80% accurate. About 5-10% of people over 70 have raised MMA levels without a B12 deficiency, so it's not so helpful in the elderly.

Although many authorities say it's the best test that's currently available for B12 deficiency it's not used as the default. That's because it requires the test to be run on a gas chromatograph - mass spectrometer, which makes it a fairly expensive test.

Some people have what's known as a functional B12 deficiency. Although there's plenty of B12 in the blood for some reason it's not getting into the cells, or the cell organelles, where it's needed to do its job. In these people blood tests for B12 are useless, but the MMA test will show if there's a functional deficiency.

Another similar test is for homocysteine. But this is more complex (the analysis needs to be done within 2 hours) so it's not done very often.

[jillc39]

what happens if the b12 is not getting into the cells?

[fbirder in reply to jillc39]

what happens if the b12 is not getting into the cells?

Then you'll have all the symptoms of B12, even with high blood levels.

There are several theoretical reasons why this may happen. One is that you have low amounts of holotranscobalamin (aka 'Active' B12). This is B12 bound to a protein called TC2. The B12 has to be in this form to be able to enter the cells. Some people don't have enough (possibly because of a problem in the TCN2 gene) so they have a functional deficiency.

[Rachel-285]

Can I ask, is there is anything that can be done to treat someone if someone has a B12 functional deficiency as surely B12 injections would be useless?

Thanks

[fbirder in reply to Rachel-285]

That's a very good question.

I'll be damned if I can think of a good answer.

[Gambit62 Administrator in reply to Rachel-285]

The only bits I've been able to find in the literature on treating functional deficiency have been references to instances where keeping levels very high worked. ie more frequent injections. This may be because what is going on isn't about nothing getting through but not enough getting through for whatever reason and keeping the levels really high - above the point where whatever is stopping the transfer beats the level that is there.

Some people have reported that lower doses more frequently seem to work for them - which may be the same thing.

Just doesn't seem to be an area that has been looked at specifically.