Pediatric emergency medicine trisk 2181 2181

TABLE 93.1
CLASSIFICATION OF ANEMIA BY RED BLOOD CELL SIZE
Macrocytic (MCV >100)
• Megaloblastic anemia: folic acid or vitamin B12 deficiency
• Liver disease (target cells)
• Reticulocytosis
• Hypothyroidism
• Myelodysplastic syndrome
• Antiretrovirals, for example, AZT
Microcytic (MCV <80)
• Iron deficiency
• Thalassemia
• Anemia of chronic disease
• Sideroblastic anemia
• Lead poisoning
Normocytic (MCV 80–100)
• Low reticulocyte count
• Iron deficiency (especially early)
• Anemia of chronic disease
• Chronic renal disease (low erythropoietin)
• Hypothyroidism, adrenal insufficiency, or hypopituitarism
• Primary bone marrow disorder
• Aplastic anemia
• Malignancy, for example, leukemia, metastases
• Myelodysplastic syndromes
• Infection, for example, parvovirus B19 (causes red cell hypoplasia or aplastic
anemia)
• Blood loss
• Hemolysis
Adapted from Zeiger RF, McGraw-Hill’s Diagnosaurus 4.0. Available online at
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Alternatively, comparing the MCV level with age-appropriate normal values allows
for classification of anemia as macrocytic, normocytic, or microcytic ( Table 93.1 ). A
reticulocyte count indicates the reactivity of the marrow, and elevated levels are often
found in blood loss and hemolysis. Decreased levels of serum haptoglobin, elevated
lactate dehydrogenase, and increased unconjugated bilirubin along with the presence of
heme in the urine suggest hemolysis.