- Sideroblastic Anemias are a diverse group of hereditary and acquired conditions caused by defects in heme synthesis and characterized by the presence of "ringed sideroblasts" within the bone marrow.
|Pathogenesis and Clinical Consequences|
- Although a wide variety of etiologies can lead to sideroblastic anemia, their common pathogenesis appears to involve defects in heme synthesis. Although this results in reduced hemoglobin production, iron delivery to erythrocytes is not attenuated, leading to a state of excess erythrocyte iron, ineffective erythropoiesis, and ultimately generalized whole-body iron overload.
- Ringed Sideroblasts
- Sideroblastic Anemias are characterized by the presence of ringed sideroblasts when the bone marrow is stained with Prussian Blue, a stain that identifies iron. In these cells a band of iron is found ringing the nucleus, representing iron-laden mitochondria.
- Hypochromic, Microcytic Anemia
- Given reduced hemoglobin production, erythrocytes are typically small and pale, observed clinically as a hypochromic microcytic anemia.
- Ineffective Erythropoiesis
- For unclear reasons, possibly due to iron-overload, erythrocytes within the marrow are prone to destruction, leading to a state of ineffective erythropoiesis that exacerbates the anemic state
- Iron Overload
- Likely secondary to the ineffective erythropoiesis, whole-body iron metabolism becomes deranged, leading to a state of whole-body iron overload and in many cases hemochromatosis