High serum folate??

[Msinnott]

For the last 5 years everytime my doctor checks my serum folate it is more than 20. With normal being more than 4. I did have a rbc folate checked a few months back and it was low normal. What would cause folate to be higher in serum than in rbc? I would think once I started taking methyl folate rbc folate would go up. Thoughts anyone??

Michelle