Microcytic anemia: MCV <80 fL)
- Metal toxicity (Lead toxicity, zinc toxicity)
- Iron deficiency anemia
- Chronic inflammation/chronic disease (typically normocytic) – Anemia of chronic inflammation.
- Reduced globin production (Thalassemias and hemoglobinopathies).
- Others: copper deficiency (rare)
- Sideroblastic anemia(eg, congenital, lead, alcohol, drugs; uncommon).
Normocytic anemia: MCV 80 to 100 fL
- Acute blood loss
- Iron deficiency anemia (early)
- Anemia of inflammation/anemia of chronic disease (eg, infection, inflammation, malignancy)
- Bone marrow suppression (may also be macrocytic)
- Bone marrow invasion (eg, leukoerythroblastic blood picture)
- Primary bone marrow disorder (aplastic anemia, myelofibrosis, myelodysplastic syndrome, infection (e.g. parvovirus B19), cancer (e.g. leukemia, multiple myeloma, metastasis)
- Bone marrow infiltration
- Acquired pure red blood cell aplasia
- Aplastic anemia
- Chronic kidney disease (low erythropoietin)
- Endocrine dysfunction (Hypothyroidism (most commonly normocytic); adrenal insufficiency; Hypopituitarism)
- Hemolysis
Macrocytic anemia: MCV >100 fL)
- Alcoholism
- Folate deficiency
- Vitamin B12 deficiency – Pernicious anemia, intestinal disease (gastrectomy ileal resection/disease, bacterial overgrowth, blind intestinal loops), Nutritional deficiency (vegans), Diphyllobothrium latum (fish tapeworm)
- Myelodysplastic Syndromes
- Liver disease (target cells)
- Acute myeloid leukemias (eg, erythroleukemia)
- Reticulocytosis
- Hemolytic anemia.
- Response to blood loss
- Response to appropriate hematinic (eg, iron, B12, folic acid). A hematinic is a med that increases the amount of hemoglobin in the blood.
- Drug-induced anemia (eg, Hydroxyurea, AZT, chemotherapeutic agents)
- Hypothyroidism (less commonly macrocytic)
- Antiretrovirals e.g. AZT
Two or more of these conditions may be present (eg, combined iron and folate deficiencies), resulting in a misleadingly normal mean corpuscular volume.