Severe neuropsychiatric symptoms due to vitamin b12 deficiency: a case of pernicious anemia or metformin use?

• Published in: Galicia-clinica Vol. 76; no. 4; pp. 178 - 180
• Main Authors: Urbano, Joana, Pimenta, Joana, Fernandes, Ana Catarina, Ferreira, Pestana
• Format: Journal Article
• Language: English
• Published: Sociedade Galega de Medicina Interna 01-12-2015
• Subjects: Megaloblastic anemia; Metformin; Neuropathy; Pernicious anemia; peuropathy; Psychosis; Vitamin B12
• ISSN: 0304-4866; 1989-3922; 1989-3922
• DOI: 10.22546/34/867

Pernicious anemia is the leading cause of vitamin B12 deficiency and
requires an early diagnose and proper treatment since it is a reversible
form of acute psychosis and demyelinating nervous system disease 1.
Less frequently, metformin therapy, especially on high doses and for long
time treatment, can also cause vitamin B12 deficit, but the coexistence of
anemia and neuropsychiatric symptoms is rarely seen.
We describe a case of a 49-year-old adult patient with type 2 diabetes
medicated with 850 mg of metformin per day, which presented a clinical
scenario of severe vitamin B12 deficiency with associated pancytopenia,
postero-lateral demyelinization of spinal cord and acute psychosis.
The investigation was initially negative for pernicious anemia, as upper
endoscopy and autoantibodies against intrinsic factor and parietal cells
were negative. After excluding other causes, and because serious vitamin
B12 deficiency associated with metformin is less frequent in patients
with short treatment duration and low daily doses, suspicion of pernicious
anemia was maintained. Six months after being discharged, he repeated
upper endoscopy with biopsy, which revealed atrophic gastritis and blood
autoantibodies became positive. He recovered completely from the neuropsychiatric
and hematological dysfunctions with parenteric vitamin B12
treatment. There are several uncommon aspects about this report, namely
the severity of the clinical presentation, with serious multiorganic failure.
Besides, it is also uncommon that a significant neuropsychiatric impairment
coexist with profound bone marrow suppression 2. Also of note is the
importance of a great level of suspicion concerning pernicious anemia,
since autoantibodies and upper endoscopy can be negative, especially
on early phases