I recently had a complete blood work up. My doctor said everything looks good. I went through the entire report. I saw that my B12 level was at the extreme level. Previously, my former GP did a DNA test to see if I needed to switch to Methyl B12, which turned out that I needed. The dosage was never brought up. I called my doctor and asked if this was a problem. He said yes, it is dangerous, you should cut your dosage. Duh!