RESUMO
Cobalamin, also known as vitamin B12, is a water-soluble vitamin. Cobalamin deficiency can be frequently seen in people all around the world. It can have non-specific symptoms, and in patients who are in a very critical state, it can lead to neurological or hematological abnormalities. While pernicious anemia used to be the main cause, it now accounts for a smaller number of cases, with food-bound cobalamin malabsorption being more common. Early diagnosis and appropriate management are crucial to avoid severe complications like spinal cord degeneration and pancytopenia. The primary method of treatment has been injections of vitamin B12 which are given through the intramuscular route but now the oral replacement therapy has also been very effective in treating the patients. There is increasing evidence linking increased levels of vitamin B12 to hematological and hepatic disorders, particularly cancers. This review has primarily highlighted the metabolism, clinical manifestations, diagnosis, and treatment of cobalamin deficiency in the past decade.