Microcytic red blood cells: Many red blood cells appear significantly smaller than the nucleus of the lymphocyte visible in the field, and smaller than normal red blood cell size (typically 6-8 µm). Hypochromic red blood cells: A prominent feature is the increased central pallor in many red blood cells, indicating reduced hemoglobin content. Anisocytosis and Poikilocytosis: There is some variation in the size (anisocytosis) and shape (poikilocytosis) of the red blood cells. Normal-appearing lymphocyte and platelets: A lymphocyte with a dense, round nucleus and scant cytoplasm is visible. Platelets appear normal in size and number within this field.
Iron deficiency leads to impaired heme synthesis, resulting in red blood cells that are smaller than normal (microcytic) and contain less hemoglobin (hypochromic). The bone marrow attempts to compensate by producing more red blood cells, but due to insufficient iron, these cells are often defective, leading to the observed morphological changes on the peripheral smear.
| Feature | Iron Deficiency Anemia | Thalassemia Trait | Anemia of Chronic Disease |
|---|---|---|---|
| MCV | Low | Low | Normal to Low |
| MCH/MCHC | Low | Low | Normal to Low |
| Ferritin | Low | Normal to High | Normal to High |
| TIBC | High | Normal | Low |
| RDW | High | Normal | Normal |
| Hb Electrophoresis | Normal | Abnormal (e.g., HbA2, HbF) | Normal |
| Peripheral Smear | Microcytic, hypochromic, anisocytosis, poikilocytosis | Microcytic, hypochromic, target cells, basophilic stippling | Normocytic/microcytic, normochromic/hypochromic |
Robbins Basic Pathology, 10th Ed, Ch 13, p. 459-461
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