Hi, I have been taking sublingual b12 for about a year now. (My lab work showed a b12 serum level of 299 and I was showing several symptoms of deficiency.) While this has helped I still do not feel great. I went back and my doctor had me get a b12 injection. About 10 minutes later I had blood drawn for blood work. My blood work showed a b12 serum level of >1500 so she said I do not need to receive the next scheduled b12 injections. Could having the injection before the blood work have given this high result?
Taking a blood sample after administration of intravenous it b12 will show falsely elevated b12 levels. Hence the decision in your case is flawed due to the sample timing error.