Sideroblastic anemia

Sideroblastic anemia: It is a hypochromic microcytic anemia characterized by the presence of ringed sideroblasts in the bone marrow. RBCs with Pappenheimer bodies, called siderocytes are seen in the peripheral blood. It may be hereditary or acquired. Hereditary form is inherited in an X-linked recessive fashion and results from defects in ALAS2 gene that is involved in heme production. Acquired sideroblastic anemia is caused by exposure to lead, isoniazid, pyridoxine deficiency, cycloserine, chloramphenicol, cyclophosphamide, autoimmune disorders, alcohol, leukemias etc. Some cases may result from a defect in the enzyme ALA synthase. Apart from symptoms related to anemia, hepatsplenomegaly may be seen. It is associated with higher risk of acute myeloid leukemia. Diagnosis is by the demonstration of ringed sideroblasts in bone marrow and siderocytes in peripheral smear. Iron studies typically show increased ferritin and serum iron. Level of enzyme delta aminolevulinic synthase in erythroblasts is decreased in sideroblastic anemia while it is normal or increased in IDA.

Anemia of chronic disease (AOCD): It is associated with diseases like tuberculosis, RA, SLE, sarcoidosis, IBD, lung abscess, cancers,DM, heart failure, HIV, endocrinopathies, renal failure etc. It may have a normochromic normocytic or hypochromic microcytic morphology. Multiple factors predispose to anemia in AOCD including insufficient erythropoietin production, improper iron metabolism from disease state, cytokines such as IL6, interferon gamma, IL1 and excess hepcidin. Diagnosis is by iron studies. Reticulocyte count is low.