I recently had my vitamin b12. Test, as per report my results are 142 pg/ml which is below the normal range (187-883), please advise what it can lead.

Brain damage / death. If you're a vegetarian and not supplementing, please reconsider your lifestyle choice. If not, your physician may begin treatment (which would be lifelong) now, or repeat the test the real danger comes with much lower levels, and he/she will want to look for a cause -- anything from stomach disease to an absorption problem. Stay pro-active.