TABLE 1

Characteristics of vitamin B₁₂ vs folate deficiency

	Vitamin B₁₂ deficiency	Folate deficiency
Etiology	Lack of intrinsic factor: pernicious anemia Malabsorption: celiac disease, prior gastric or ileal surgery Dietary deficiency less common	Dietary deficiency: alcoholism, countries without food fortification Malabsorption: developed countries Increased demand: pregnancy, hemolytic anemia, eczema
Clinical presentation	Hematologic findings: cytopenias Neuropsychiatric symptoms: paresthesias, decreased proprioception and vibratory sense, dementia, confusion	Hematologic findings: cytopenias
Evaluation	Clinical history and physical examination: symptoms secondary to anemia and hemolysis, neurologic symptoms Laboratory testing: serum vitamin B₁₂, methylmalonic acid, homocysteine, antiparietal cell and anti-intrinsic factor antibodies, serum gastrin Gastric biopsy for suspected pernicious anemia	Clinical history and physical examination: similar to vitamin В₁₂ deficiency, except no neurologic symptoms Laboratory testing: serum folate, red blood cell folate, methylmalonic acid, homocysteine
Differential diagnosis	Other macrocytic anemias without megaloblastic features: liver disease, thyroid dysfunction, alcohol abuse Myelodysplastic syndrome, acute myeloid leukemia Nitrous oxide exposure Medication effect	Other macrocytic anemias without megaloblastic features: liver disease, thyroid dysfunction, alcohol abuse Myelodysplastic syndrome, acute myeloid leukemia Medication effect
Treatment	Parenteral vitamin В₁₂ 1-2 times per week until symptoms improve, then monthly High-dose oral vitamin B₁₂ daily	Oral folate daily
Monitoring and follow-up	Clinical follow-up for improvement of neurologic symptoms Monitor hematologic response: complete blood cell count Pernicious anemia: consider monitoring methylmalonic acid	Monitor hematologic response: complete blood cell count