II. Causes
-
Iron Deficiency Anemia (most common)
- Decreased Serum Iron level
- Increased Total Iron Binding Capacity
- Decreased Transferrin Saturation
-
Thalassemia
- Normal iron studies
- Differentiated with Hemoglobin electrophoresis
-
Anemia of Chronic Disease
- Decreased Serum Iron, TIBC and Transferrin Saturation
-
Sideroblastic Anemia
- Similar workup as with Thalassemia
- Lead Poisoning
- Copper Deficiency
- Zinc Toxicity
- Hemoglobinopathy
III. Labs
-
Complete Blood Count
- See Hemoglobin Cutoffs for Anemia
- See Hematocrit Cutoffs for Anemia
-
Mean Corpuscular Volume (MCV) <80
- See MCV Cutoffs for Microcytic Anemia
- MCV cutoff varies by age and per reference
-
Serum Iron
- Decreased in Iron Deficiency Anemia and Anemia of Chronic Disease
-
Total Iron Binding Capacity (TIBC)
- Increased in Iron Deficiency Anemia
- Decreased in Anemia of Chronic Disease
-
Transferrin Saturation
- Near complete saturation in Sideroblastic Anemia
- Less than 5% saturated in Iron Deficiency Anemia
-
Ferritin Level
- Ferritin <15 ng/ml suggests Iron Deficiency Anemia
- Ferritin is acute phase reactant and also elevated in chronic inflammation
- Use cutoff of <50 ng/ml to diagnose Iron Deficiency Anemia when comorbid inflammatory condition present
-
Reticulocyte Index <1% (Reticulocytopenia)
- See Anemia for causes of Reticulocytosis
-
Mean Corpuscular Volume to Red Blood Cell Count ratio
- See Mentzer Index
- Ratio <13: Thalassemia
- Ratio >13: Iron Deficiency Anemia, Hemoglobinopathy
IV. Labs: Hemoglobin Electrophoresis
- Indications
- Suspected Hemoglobinopathy (e.g. Thalassemia)
- Normal Serum Iron, Transferrin Saturation, and TIBC (esp. in young patients)
- Interpretation
- Increased Hemoglobin A2 Level
- Normal Hemoglobin A2 Level
- Sideroblastic Anemia
- Alpha-Thalassemia trait