The table below is a quick summary of how changes in the mean cell volume (MCV) and mean cell hemoglobin concentration (MCHC) can guide us as to the mechanism and potential cause of an anemia.
|Normocytic||Normochromic||Mild to moderate||No||Decreased production||Anemia of inflammatory disease (most common; due to inflammatory cytokines which suppress erythropoiesis and sequester iron via increasing hepcidin; many diseases including neoplasia, inflammation, liver disease), chronic renal disease (decreased erythropoietin), endocrine disease (hypothyroidism, hypoadrenocorticism), ineffective hematopoiesis (infectious agents, e.g. Ehrlichia canis, drugs, histiocytic sarcoma, lymphoma, immune-mediated), severe nutritional deficiencies.|
|Normocytic||Normochromic||Severe||No||Decreased production||Primary bone marrow problem (e.g. non-regenerative immune-mediated anemia, pure red blood cell aplasia, or precursor directed immune-mediated anemia [PIMA], hematopoietic neoplasia, infiltrative neoplasia, bone marrow aplasia), drugs (e.g. immune response against erythropoietin therapy, idiosyncratic drug reaction), some forms of chronic renal disease (particularly congenital disorders), multifactorial anemia (more than one mechanism).May or may not be accompanied by other cytopenias (neutropenia, thrombocytopenia).|
|Normocytic||Normochromic||Any||Yes||Hemorrhage or hemolysis||Many causes|
|Macrocytic||Normochromic to hypochromic||Any||No||Decreased production with abnormal DNA metabolism||Vitamin B12 deficiency, folate deficiency, cobalt deficiency (molybdenum excess), feline leukemia virus infection in cats, congenital dyserythropoietic anemia, myelodysplastic syndrome, drugs that interfere with DNA metabolism (e.g. hydroxyurea), non-regenerative immune-mediated anemia (precursor directed immune mediated anemia, PIMA), inherited defects in RBC membrane (hereditary stomatocytosis)|
|Macrocytic||Hypochromic||Any||Yes||Hemorrhage or hemolysis||Many causes of hemorrhage or hemolysis. Regeneration may be mild in some causes.|
|Microcytic||Normochromic to hypochromic||Any||No||Decreased production with defective hemoglobin production||Iron deficiency, copper deficiency (zinc excess, rare), vitamin B6 deficiency (experimental), portosystemic shunts (frequently not anemic), congenital dyserythropoiesis (English Springer Spaniels), band 4.1 deficiency with hereditary elliptocytosis (dog), drugs or toxins that interfere with hemoglobin production (e.g. chronic lead poisoning), PIMA.|
|Microcytic||Hypochromic||Any||Yes||Iron deficiency||Chronic external blood loss, nutritional iron deficiency, copper deficiency (zinc excess).|