ICD-11

A disease caused by inadequate dietary intake of vitamin B12, impaired absorption of vitamin B12, surgical removal of the small bowel, coeliac disease or inherited mutations affecting absorption of vitamin B12. This disease is characterised by decreased levels of vitamin B12 in the body presenting with or without anaemia. This disease may present with fatigue, pallor, dizziness, seizures, or symptoms of dementia. Confirmation is by identification of decreased levels of vitamin B12 in a blood sample.

This is a hereditary low blood level of vitamin B12. It can cause permanent damage to nervous tissue if left untreated long enough. Vitamin B12 itself was discovered through investigation of pernicious anaemia, which is an autoimmune disease that destroys parietal cells in the stomach that secrete intrinsic factor.