Vegan Diet as a Neglected Cause of Severe Megaloblastic Anemia and Psychosis

A 47-year-old woman with a 5-year history of psychosis treated with olanzapine, accompanied by her mother, sought medical advice for fatigue and dyspnea of progressive onset lasting for 4 months. On physical examination, the patient was pale with pitting edema of lower extremities. Her speech was reduced, her attention and concentration impaired, and she reported visual hallucinations. She declined to answer questions and to participate in a mini-mental test evaluation. No lymphadenopathy or hepatosplenomegaly were palpable. Neurologic examination was unremarkable. The blood cell count showed a hemoglobin level of 4.0 g/dL (mean corpuscular volume 112 fL, reticulocyte cell count 58,000/mm³) and a platelet count of 110,000/mm³, a normal white blood cell count but hypersegmented neutrophils on blood marrow smear. The lactate dehydrogenase level was 2,418 IU/L (normal <250), total bilirubin 23 μmol/l (normal <17), and haptoglobin <0.08 g/L (normal <0.55). Vitamin B₁₂ blood level was<83 pm/L (normal >187pmol/L) and serum homocysteine 80.8 μmol/L (normal <15). Thyroid-stimulating hormone level was normal. Direct Coombs test was negative. A bone marrow smear demonstrated erythroid hyperplasia with megaloblastic maturation, hypersegmented neutrophils, and megaloblasts consistent with vitamin B₁₂ deficiency. Upper gastrointestinal endoscopy with gastric biopsies was normal, and serum parietal cell antibodies were not detected. Search for a medical cause of confusion including brain computed tomography (CT) scan and electroencephalogram was negative. Diagnosis of vitamin B₁₂-deficiency anemia with psychotic disorder was established. Finally her mother revealed that the patient was following a strict vegan diet for 7 years. Oral supplementation at the dose of 1,000 μg vitamin B₁₂ (cyanocobalamin) daily during 10 days then every 10 days led to normalization of blood abnormalities within 3 months. Six months later her psychiatric symptoms had relieved with control of delirious and negative behavior and a mini-mental test evaluation of 30/30. The patient was then lost to follow-up.