​Differential Diagnosis of Megaloblastic Anemia due to Folate Deficiency 
• With normal intestinal mucosa
• With mucosal abnormalities: tropical and nontropical sprue, regional enteritis
• Some drugs
• Physiologic: pregnancy and lactation, prematurity, infancy
• Pathologic: intrinsic hematologic disease (autoimmune hemolytic disease), drugs, malaria; hemoglobinopathies (Sjögren’s syndrome, thalassemia), red blood cell (RBC) membrane defects (hereditary spherocytosis, paroxysmal nocturnal hemoglobinopathy); abnormal hematopoiesis (leukemia/lymphoma, myelodysplastic syndrome, agnogenic myeloid metaplasia with myelofibrosis); infiltration with malignant disease; dermatologic (psoriasis)
• Inadequate cellular utilization: folate antagonists (methotrexate), hereditary enzyme deficiencies involving folate
• Drugs (multiple effects on folate metabolism): alcohol, sulfasalazine, triamterene, pyrimethamine, trimethoprimsulfamethoxazole, diphenylhydantoin, barbiturates
• Defective cellular folate uptake: familial aplastic anemia (rare)
• Decreased dietary intake: poverty and famine (associated with kwashiorkor, marasmus), institutionalized individuals (psychiatric/nursing homes), chronic debilitating disease/goat’s milk (low in folate), special diets (slimming), cultural/ethnic cooking techniques (food folate destroyed) or habits (folate-rich foods not consumed)
• Congenital folate malabsorption (rare)