Table 2.

Common causes of ineffective erythropoiesis and tests used to exclude them

Megaloblastic anemia	Normal vitamin B12 and folic acid level
Myelodysplastic syndrome	No dysplastic features in the bone marrow
Acute myeloid leukemia, FAB-type M6	No blasts
Myelofibrosis	No bone marrow fibrosis
Sideroblastic anemia (inherited/acquired)	No microcytosis, no response to pyridoxine; causes of acquired sideroblastic anemia ruled out
Thalassemia syndromes	Normal hemoglobin electrophoresis
Hereditary spherocytosis	Normal osmotic fragility
Pyruvate kinase deficiency	Normal pyruvate kinase level