Monday, January 20, 2014

Metformin induced B12 deficiency

Arch Int Med 2006 166: 1975-9

Retrospective study found B12 deficiency correlated with dose and duration of metformin therapy.  B12 deficit defined as less than 150.  N was 155 patients.  Mechanism is inhibition of calcium dependent ileal absorption of B12-intrinsic factor,  which calcium supplementation can reverse. 

Along with acid inhibitors (PPI's H2 blockers, metformin is most common cause of B12 deficiency.  Odds ratio is 2.88 for each i gram increment and 2.39 for use > 3 years. 

In one study 6 percent of cases of B12 deficiency had associated metformin use (Br M J 1971) ,

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