Sideroblastic anemia: This is a hypochromic microcytic anemia characterized by ringed sideroblasts in the bone marrow. In the peripheral blood, you may see RBCs with Pappenheimer bodies; these cells are called siderocytes.
It may be hereditary or acquired.
The hereditary form is inherited in an X-linked recessive pattern and results from defects in the ALAS2 gene, which is involved in heme production.
Acquired sideroblastic anemia can be 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.
In addition to symptoms related to anemia, hepatosplenomegaly may be seen. It is associated with a higher risk of acute myeloid leukemia.
Diagnosis is made by demonstrating ringed sideroblasts in the bone marrow and siderocytes on the peripheral smear. Iron studies typically show increased ferritin and increased serum iron. The level of delta aminolevulinic synthase in erythroblasts is decreased in sideroblastic anemia, while it is normal or increased in IDA.
Anemia of chronic disease (AOCD): This anemia is associated with conditions such as tuberculosis, RA, SLE, sarcoidosis, IBD, lung abscess, cancers, DM, heart failure, HIV, endocrinopathies, renal failure, etc. Morphology may be normochromic normocytic or hypochromic microcytic.
Multiple factors contribute to anemia in AOCD, including insufficient erythropoietin production, impaired iron metabolism due to the disease state, cytokines such as IL6, interferon gamma, IL1, and excess hepcidin.
Diagnosis is made using iron studies. The reticulocyte count is low.
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