Severe<unk>  is defined as a hemoglobin level of 5 to 7 g/dL with symptoms of hypoperfusion including lactic acidosis, base deficit, shock, hemodynamic instability, or coronary ischemia
Assess for any signs of bleeding or trauma before considering other causes of chronic<unk> .
CBC for evaluation, look at MCV
Microcytic: Iron Levels, Reticulocyte Count, Ferritin, TIBC
Macrocytic: Folate Level, B12 Level, Reticulocyte Count
Microcytic: Iron Levels, Reticulocyte Count, Ferritin, TIBC
Macrocytic: Folate Level, B12 Level, Reticulocyte Count
RDW high → evaluate Ferritin, which is a measurement of iron storage
Ferritin low: Iron deficiency<unk> 
Ferritin normal:<unk>  chronic disease or sideroblastic<unk>  (e.g. lead poisoning)
RDW normal
RBC count low:<unk>  chronic disease, hypothyroidism, Vitamin C deficiency
RBC count normal or high: Thalassemia
Ferritin low: Iron deficiency<unk> 
Ferritin normal:<unk>  chronic disease or sideroblastic<unk>  (e.g. lead poisoning)
RBC count low:<unk>  chronic disease, hypothyroidism, Vitamin C deficiency
RBC count normal or high: Thalassemia
Retic count normal
RDW normal:<unk>  chronic disease,<unk>  of renal insufficiency
RDW high: Iron, Vit B12, or folate deficiency
Retic count high
Coombs Positive: Autoimmune cause
Coombs negative: G6PD, SCD, spherocytosis, microangiopathic hemolysis
RDW normal:<unk>  chronic disease,<unk>  of renal insufficiency
RDW high: Iron, Vit B12, or folate deficiency
Coombs Positive: Autoimmune cause
Coombs negative: G6PD, SCD, spherocytosis, microangiopathic hemolysis
RDW high: Vit B12 or folate deficiency
RDW normal: ETOH abuse, liver disease, hypothyroidism, drug induced, myelodysplasia
Anemia
Hemorrhage
Pancytopenia
Hereditary
Leukopenia
Acquired
Polycythemia
Microangiopathic Hemolytic Anemia 