Vitamin B12 deficiency - A 21st century perspective 

Vitamin B12 deficiency is a common condition which can present with non-specific clinical features, and in severe cases with neurological or haematological abnormalities. Although classically caused by pernicious anaemia, this condition now accounts for a minority of cases and vitamin B12 deficiency occurs most often due to food-bound cobalamin malabsorption. Since missing the diagnosis can result in potentially severe complications, including degeneration of the spinal cord and pancytopaenia, vitamin B12 deficiency must be diagnosed early and managed appropriately. Intramuscular injections have been the mainstay of treatment, but oral replacement therapy can be effective in many cases. There is accumulating evidence that high vitamin B12 levels (values varied from 350-1,200 pmol/l) are associated with haematological and hepatic disorders, in particular with malignancy. This review focuses on the developments in the clinical features and management of vitamin B12 deficiency over the last decade.