What was "high"? There is no upper limit to B12.
Lab ranges are just estimates, and really, the lows are concerning...many people are walking around with low values, and their doctors call it "normal"
You are in another country, yes? Post your values here along with the concentration either pg/ml or pmol/L and I can convert it for you.
Most countries but not all use SI units:
Dr. Snow in US wrote the major turning point paper on B12 in
1999, and in it he found that people with moderately normal B12 could still present with neurological symptoms. He suggests
therefore to take B12, extra.
His paper link can be found here:
If you are interested further please read the whole B12 link at PN in the stickies. I have genetic information there as well that
leads to poor B12 utilization.
High B12 readings, above 1000 US units may point to other disease states in the body. Liver problems, kidney problems, blood cancers, etc. When this happens and NO vitamins are being taken, it is a warning for the doctor to look for the culprit.
But the levels themselves are not "toxic"...they are only a flag.