1. Complete blood cell count

2. Reticulocyte count

3. Peripheral blood smear

Corrected reticulocyte count <2% or absolute reticulocyte count <100,000/μL

Low MCV, Normal RDW = Anemia of chronic disease

Normal MCV, Normal RDW = Anemia of chronic disease

High MCV, Normal RDW = Chemotherapy/antivirals/alcohol Aplastic anemia

Low MCV, High RDW = Iron deficiency anemia

Normal MCV, High RDW = Early iron, folate, or vitamin B₁₂ deficiency Myelodysplasia Dimorphic anemia

High MCV, High RDW = Folate or vitamin B₁₂ deficiency Myelodysplasia

Send specific diagnostic tests as appropriate (iron studies, folate and B₁₂ levels, erythropoietin level)

Corrected reticulocyte count >2% or absolute reticulocyte count ≥100,000/μL

Send specific diagnostic tests as appropriate

Differential diagnoses/tests to obtain:

Hemoglobinopathies/hemoglobin electrophoresis

Immune hemolytic anemias/direct antiglobulin test

Infectious causes of hemolysis/thick smear, serology

Membrane abnormalities/osmotic fragility; PNH screen

Metabolic abnormalities/Heinz body prep; G6PD assay

Mechanical hemolysis/coagulation tests