I have never heard of "active b12 test" Is it the same thing as an MMA? Does it matter if b12 treatment has already been started? Iam fine as long as I take methly b12, by jarrow everyday. If I miss a few days my feet and hands start to vibrate and I get twitches in my lower legs. But supposedly, by my MMA, I have built up enought stores. What I don't seem to be able to comprehend is: if your body stores 5-6 years worth of b12 and it takes a long time to become depleated how is it possible to build it back up so fast? And if the stores are built up why would I have symptoms after only missing a few days?