title: [Diagnosis of vitamin B12 deficiency: a case illustrating diagnostic pitfalls].
abstract: BACKGROUND
  Vitamin B12 deficiency is a longstanding public health problem which affects more than 20% of the elderly population. Among multiple causes of vitamin B12 deficiency, Biermer's disease is currently mentioned in about 25% of the cases.
  
  
  METHODS
  We report the case of a 71-year-old woman, taking folate substitution therapy who, over 2 years, progressively developed spinal combined sclerosis, subacute dementia and severe neuropathy leading to a bedridden state. The initial assessment revealed normocytic anemia, without vitamin B12 deficiency and without increased plasma level of biological markers. The plasma folate level was high. Vitamin B12 assay was repeated leading to the diagnosis of deficiency associated with the presence of intrinsic factor antibodies.
  
  
  CONCLUSIONS
  This observation illustrates the broad spectrum of clinical presentations of vitamin B12 deficiency. In the present case, the lack of sensitivity of biological markers delayed diagnosis and had a dramatic impact on outcome. This case highlights the importance of promoting factors such as isolated folate substitution in B12 deficient patients.
authors.affiliation: Centre de référence des maladies neuromusculaires et de la SLA, hôpital de La Timone, 264, rue Saint-Pierre, 13385 Marseille cedex 20, France. gutierrezmariana4@gmail.com
authors.forename: M
authors.initials: M
authors.lastname: Gutierrez
authors.forename: J
authors.initials: J
authors.lastname: Franques
authors.forename: A
authors.initials: A
authors.lastname: Faivre
authors.forename: L
authors.initials: L
authors.lastname: Koric
authors.forename: L
authors.initials: L
authors.lastname: Chiche
authors.forename: S
authors.initials: S
authors.lastname: Attarian
authors.forename: J
authors.initials: J
authors.lastname: Pouget
mesh_terms: D000368:Aged; D000740:Anemia / Q000175:diagnosis; D001513:Beds; D001921:Brain / Q000473:pathology; D003704:Dementia / Q000209:etiology; D003937:Diagnosis, Differential; D005260:Female; D005492:Folic Acid / Q000097:blood; D007839:Functional Laterality; D006801:Humans; D008279:Magnetic Resonance Imaging; D009043:Motor Activity / Q000502:physiology; D012598:Sclerosis / Q000209:etiology; D014805:Vitamin B 12 / Q000097:blood / Q000627:therapeutic use; D014806:Vitamin B 12 Deficiency / Q000097:blood / Q000175:diagnosis* / Q000503:physiopathology / Q000523:psychology
chemical_list: D005492:Folic Acid; D014805:Vitamin B 12