Is a B12 Level of 250 Low or Borderline?
                                
                                
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                                    4 min read                                
                            
                                According to sources including StatPearls, a serum B12 level between 200 and 300 pg/mL is considered borderline, not definitively low. A result of 250 pg/mL falls squarely in this ambiguous range, meaning it requires additional medical evaluation rather than an automatic diagnosis of deficiency.