Red Blood Cell Abnormalities Seen on Stained Smear
| Descriptive Term | Observation | Significance |
|---|---|---|
| Macrocytosis | Cell diameter > 8 µm MCV* > 95 µm3 | Megaloblastic anemias Severe liver disease Hypothyroidism |
| Microcytosis | Cell diameter < 6 µm MCV < 80 µm3 MCHC† < 27 | Iron-deficiency anemia Thalassemias Anemia of chronic disease |
| Hypochromia | Increased zone of central pallor | Diminished Hgb content |
| Hyperchromia | Microcytic, hyperchromic cells Increased bone marrow stores of iron | Chronic inflammation Defect in ability to use iron for Hgb synthesis |
| Polychromatophilia | Presence of red cells not fully hemoglobinized | Reticulocytosis |
| Poikilocytosis | Variability of cell shape | Sickle cell disease Microangiopathic hemolysis Leukemias Extramedullary hematopoiesis Marrow stress of any cause |
| Anisocytosis | Variability of cell size | Reticulocytosis Transfusing normal blood into microcytic or macrocytic cell population |
| Leptocytosis | Hypochromic cells with small central zone of Hgb ("target cells") | Thalassemias Obstructive jaundice |
| Spherocytosis | Cells with no central pallor, loss of biconcave shape | Loss of membrane relative to cell volume Hereditary spherocytosis |
| Schistocytosis | MCHC high | Accelerated red blood cell destruction by reticuloendothelial system |
| Acanthocytosis | Presence of cell fragments in circulation | Increased intravascular mechanical trauma Microangiopathic hemolysis |
| Echinocytosis | Irregularly spiculated surface | Irreversibly abnormal membrane lipid content Liver disease Abetalipoproteinemia |
| Regularly spiculated cell surface | Reversible abnormalities of membrane lipids High plasma-free fatty acids Bile acid abnormalities Effects of barbiturates, salicylates, and so on | |
| Stomatocytosis | Elongated, slitlike zone of central pallor | Hereditary defect in membrane sodium metabolism Severe liver disease |
| Elliptocytosis | Oval cells | Hereditary anomaly, usually harmless |
Source: Adapted from Sacher, RA, and McPherson, RA: Widmann's Clinical Interpretation of Laboratory Tests, ed 11. FA Davis, Philadelphia, 2000 p. 68, with permission.
* Mean corpuscular volume.
† Mean corpuscular hemoglobin concentration.