Hi There, I really tried to surf through all the information on this site for the answer, but had no luck. A little background. About 6 months ago or so I was having extreme tingling and numbness in hands and feet and my regular GP tested serum B12 and folate. B12 was elevated... 1036, I believe. She assumed I was supplementing at the time (I wasn't) and sort of wrote it off. 2 months later I moved to a new city and started seeing a functional med guy who guessed that due to my history of vegetarian and veganism and my gastro problems that I likely had a functional B12 deficiency. He started me on methyl and folate. Within a few weeks symptoms subsided. A few weeks into the treatment I started feeling crappy and realized it was a potassium issue, upped my potassium and it went away. Now, 3 months or so after treatment I have been feeling insanely tired for about 5 or 6 days. I have had a return of tingling in extremities, have muscle spasms and just generally feel beaten down. I assumed it was potassium again and upped my potassium food intake to around 4600, which has not helped much. So, I am thinking I want to re-test and do MMA as well this time to be sure that it is in fact a B12 deficiency we are dealing with and that I am not barking up the wrong tree. So, how long do I need to cease supplementing B12 before testing? Or do I not at all because we want to see what is actually being absorbed? Any thoughts would be greatly appreciated!!