Classification of anemia for gastroenterologists

Table 6 Differential diagnosis of anemia from a gastrointestinal point of view

Gastrointestinal causes of anemia

Microcytic anemia

Iron deficiency

Decreased iron absorption

Frequent: Celiac disease, gastrectomy, H pylori colonization

Infrequent: Bowel resection, bacterial overgrowth

Occult gastrointestinal blood loss

Frequent: aspirin and nonsteroidal anti-inflammatory drug use, colonic carcinoma, gastric ulceration, angiodysplasia, inflammatory bowel diseases

Infrequent: esophagitis, esophageal carcinoma, gastric antral vascular carcinoma, small bowel tumors, ampullary carcinoma, Ancylomasta duodenale

Non-gastrointestinal blood loss

Frequent: menstruation, blood donation, ACD

Infrequent: Hematuria, epistaxis

Sideroblastic anemia (alcohol, lead, drugs), vitamin B6

ACD

Normocytic anemia

Frequent: ACD (liver disease, renal insufficiency, malignancy, nutritional deficiency, drug effects, alcoholism, recent trauma or surgery, iron deficiency

Infrequent: primary bone marrow disorder

Macrocytic anemia

Non-megaloblastic

Systemic disease:

Frequent: liver disease, alcoholism

Infrequent: primary bone marrow disease (myelodysplastic syndrome, aplastic anemia), metastatic infiltration, hemolytic anemia, hypothyroidism

Megaloblastic anemia

Vitamin B12 deficiency: pernicious anemia, gastrectomy, hereditary deficiency of intrinsic factor, inflammatory bowel disease, primary intestinal malabsorptive disorders, parasitic colonization, nutritional deficiencies

Folate deficiency: diet poor in folates, regional enteritis, Whipple’s disease, scleroderma, amyloidosis, increase requirements (liver disease, hemolytic anemia)

Antifolate drugs: methotrexate