5 year old DS has elevated levels of b12 - two blood samples taken several months apart have found a level of approx 1200. It's been suggested that we wait several months and get a third blood sample which will be sent to another laboratory. Other bloods are apparently in normal ranges. I am worried, having googled this (there was mention of cancer and bone marrow problems and all sorts of genetic problems). I wasn't able to get back in touch yet with the doctor to ask what they are ruling out or considering.. DS1 has some developmental delays.