Microcytic Anemias
Microcytic anemia
Definition
Hb < 12 g/dL (F) or < 13 g/dL (M) with mean cell volume (MCV) < 80 fL
Differential diagnosis
- Most common diagnoses include:
- Iron deficiency anemia
- Thalassemia
- Anemia of inflammation
- Less common causes include:
- Sideroblastic anemia
- Lead poisoning
- Hyperthyroidism
- Fragmentation syndrome
Peripheral smear findings
| Condition | Findings |
|---|---|
| Iron deficiency anemia | Size Microcytosis Anisocytosis Staining Hypochromia Few polychromatophilic cells Shapes Elliptocytes Fish-shaped cells Inclusions Typically none |
| Thalassemia minor | Size Microcytosis Staining Mostly normochromic +/- Increased polychromatophilic cells Shapes Normal Inclusions Basophilic stippling |
| Thalassemia major | Size Microcytosis Marked anisocytosis Staining Marked hypochromia Increased polychromatophilic cells Shapes Marked poikilocytosis, including: Fragments Target cells Inclusions Nucleated RBCs Basophilic stippling |
| Anemia of inflammation | Size +/- Microcytosis Staining +/- Hypochromia Few polychromatophilic cells Shapes Depends on underlying disease Inclusions Depends on underlying disease Other: Rouleaux |
| Congenital sideroblastic anemia | Size Microcytosis Anisocytosis (RBC dimorphism) Staining Hypochromia Shapes Normal Inclusions Basophilic stippling Nucleated RBCs |
Examples of peripheral smear findings
- Iron deficiency anemia
- Thalassemia intermedia
Additional TBP resources
- Peripheral smears of iron deficiency
- Infographic on microcytosis
- Discriminant formulas for distinguishing iron deficiency anemia from thalassemia