hematology and oncology
Sideroblastic Anemias
Introduction
Sideroblastic anemias are a diverse group of anemias characterized by the presence of increased serum iron, ferritin, and transferrin saturation as well as ringed sideroblasts (erythroblasts with perinuclear iron-engorged mitochondria). Symptoms are those of anemia and include fatigue and lethargy. Diagnosis is with complete blood count, reticulocyte count, and peripheral blood smear as well as iron studies and bone marrow examination. Treatment requires stopping causative substances and giving vitamin supplements and erythropoietin. (See also Overview of Decreased Erythropoiesis .) Sideroblastic anemias may be Acquired Congenital Acquired sideroblastic anemia is frequently associated with Myelodysplastic Syndrome (MDS) (but may be caused by medications or toxins) and causes a normocytic or macrocytic anemia. Congenital sideroblastic anemia is caused by one of numerous X-linked or autosomal mutations and is usually a microcytic, hypochromic anemia but may be normocytic. Sideroblastic anemias are iron-utilization anemias, which are characterized by inadequate mitochondrial utilization of iron due to impaired heme synthesis despite the presence of adequate or increased amounts of iron. Sideroblastic anemias are sometimes characterized by the presence of polychromatophilia (indicative of an increased number of reticulocytes) and stippled red blood cells (siderocytes) containing iron-laden granules (Pappenheimer bodies). In both acquired and congenital sideroblastic anemia, heme synthesis is impaired due to the inability to incorporate iron into protoporphyrin IX, leading to the formation of ringed sideroblasts. 