I don't understand...

[MiniMum97]

1. Why would supplementation of b12 affect an MMA/homocysteine test. Are these measures not a reaction to b12 and wouldn't be lower if supplementing?

2. If your b12 deficiency is not caused by your body not being able to absorb it (i.e. You can get it into your blood via tablets as shown by a serum test) and is instead cause by your cells not being able to take it up (functional deficiency??) why wouldb12 injections make any difference to that given all that they do is get b12 into your blood?

Confused!

[fbirder]

1. MMA and hCys are the biochemicals used up in (I.e, they are substrates go) the two main reactions mediated by B12. If those reactions don't take place at the normal rate then the levels of those substrates will increase. If not enough B12 is getting into the body (or into the cell) then the levels of both substrates will rise.

If supplementation with B12 raises blood levels then, assuming a B12 deficiency was the problem, the levels of both substrates should fall.

2. If you do suffer from a functional deficiency (which appears to be quite unusual) then you will have high levels of B12 in the blood but low levels in the cells. This would be shown by high levels of one/both of MMA and hCys. In such a case injections may help by getting very high blood levels, which may help more get into the cells.

[Serendipity16 in reply to fbirder]

Sorry to piggyback the post. My understanding is that homocysteine is taken as blood test, kept on ice and processed within 2 hours. Is this right? If this is not kept on ice or processed in the correct time, what would happen to the result? would it be lower or higher?