Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content + Download Section PDF Listen ++ For further information, see CMDT Part 13-05: Sideroblastic Anemia + Key Features Download Section PDF Listen +++ ++ Heterogeneous group of disorders in which reduced hemoglobin synthesis occurs because of reduced ability to synthesize heme or an impaired ability to incorporate heme into protoporphyrin IX Iron accumulates, particularly in mitochondria Modern classification divides sideroblastic anemia into two categories Dyserythropoiesis (ie, hypohepcidinemia) Transfusion-dependence (eg, myelodysplastic syndrome, thalassemia) Most often it is a subtype of myelodysplastic syndrome Other causes include chronic alcoholism, lead poisoning, copper deficiency (hypocupremia), drugs (isoniazid and chloramphenicol), and chronic infection or inflammation Inherited forms are usually X-linked but rare recessive forms have been documented + Clinical Findings Download Section PDF Listen +++ ++ Symptoms of anemia; no other specific clinical features Hypocupremia Normocytic anemia in two-thirds of cases; macrocytic in remainder Zinc level is usually elevated Neutropenia or thrombocytopenia may be present Myelopathy or demyelinating peripheral neuropathy in some patients + Diagnosis Download Section PDF Listen +++ ++ Anemia usually moderate, hematocrit 20–30% Mean corpuscular volume Usually normal or slightly increased in sideroblastic subtype of myelodysplastic syndrome Usually low in other subtypes (especially inherited forms), leading to confusion with iron deficiency Peripheral blood smear characteristically shows dimorphic population of RBCs: 1 normal and 1 hypochromic Coarse basophilic stippling of RBCs and serum lead level elevated in lead poisoning Bone marrow iron stain shows generalized increase in iron stores and ringed sideroblasts (RBCs with iron deposits encircling the nucleus) and marked erythroid hyperplasia (resulting from ineffective erythropoiesis) Serum iron level and transferrin saturation are high + Treatment Download Section PDF Listen +++ ++ Occasionally, transfusion is required for severe anemia Recombinant erythropoietin therapy is not usually effective Oral pyridoxine (50–200 mg/day) occasionally useful Removal of offending toxins and drugs is needed in the secondary acquired forms Hypocupremia: administer copper sulfate (2.5 mg orally twice daily) Associated with high hematologic response rate but low neurologic response rate Exogenous or endogenous zinc exposure needs to be eliminated