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Sideroblastic anemia or sideroachrestic anemia is a disease in which the bone
marrow produces ringed sideroblasts rather than healthy RBCs (erythrocytes).
Caused either by:-
1- genetic disorder
2- myelodysplastic syndrome,
Can evolve into hematological malignancies (especially acute myelogenous
the body has iron available but cannot incorporate it into hemoglobin, which
RBCs need to transport oxygen efficiently.
Sideroblasts are atypical, abnormal nucleated erythroblasts with granules of iron
accumulated in perinuclear mitochondria.
Sideroblasts are seen in aspirates of bone marrow.
Ring sideroblast are named because of the arrangement of the iron granules in a
ring form around the nucleus.
Grouped on Morphology three types of sideroblasts:-
1. Type 1 sideroblasts: fewer than 5 siderotic granules in the cytoplasm
2. Type 2 sideroblasts: 5 or more siderotic granules, but not in a perinuclear
3. Type 3 or ring sideroblasts: 5 or more granules in a perinuclear position,
surrounding the nucleus or encompassing at least one third of the nuclear
Sideroblastic anemia is typically divided into subtypes based on its cause.
Hereditary or congenital sideroblastic anemia may be X-linked or
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Skin paleness, fatigue, dizziness, and enlarged spleen and liver. Heart disease,
liver damage, and kidney failure can result from iron buildup in these organs.
failure to completely form heme molecules in the mitochondrion lead to
deposits of iron in the mitochondria that form a ring around the nucleus of the
Sometimes the disorder represents a stage in evolution of a generalized bone
marrow disorder that may ultimately terminate in acute leukemia.
Toxins: lead, copper, or zinc poisoning
induced: ethanol, isoniazid, chloramphenicol, cycloserine, Linezolid, oral
Nutritional: pyridoxine (Vitamin B6) or copper deficiency
Diseases: Rheumatoid arthritis or multiple myeloma
Genetic: ALA synthase deficiency (X-linked, associated with ALAS2)
1. Ringed sideroblasts are seen in the bone marrow.
2. The anemia is moderate to severe
3. Dimorphic with marked anisocytosis and poikilocytosis.Basophilic
stippling is marked and target cells are common. Pappenheimer bodies are
4. MCV is decreased (i.e., a microcytic anemia).
5. RDW is increased with the red blood cell histogram shifted to the left.
6. Leukocytes and platelets are normal.
7. Bone marrow shows erythroid hyperplasia with a maturation arrest.
8. In excess of 40% of the developing erythrocytes are ringed sideroblasts.
9. Serum iron, percentage saturation and ferritin are increased. The
10. TIBC is normal to decreased.
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11. Stainable marrow hemosiderin is increased.
1. Increased ferritin levels
2. Normal total iron-binding capacity
3. Hematocrit of about 20-30%
4. Serum Iron: High
5. High transferrin saturation
6. MCV is usually normal or low.
7. With lead poisoning, see coarse basophilic stippling of RBCs on peripheral
8. Specific test: Prussian Blue stain of RBC in marrow. Shows ringed
9. Can also cause microcytic hypochromic anemia.
1. anemia is so severe that support with transfusion is required.
2. Patients usually do not respond to erythropoietin therapy.
3. improved heme level by moderate to high doses of Vitamin
4. Severe cases of SBA, bone marrow transplant with limited information
about the success rate.
5. In the case of isoniazid-induced sideroblastic anemia, the addition of B6 is
sufficient to correct the anemia.
6. Desferrioxamine is used to treat iron overload from transfusions.
7. Bone Marrow Transplant (BMT) is the last possible treatment.
Course and prognosis
Sideroblastic anemia’s are often described as responsive or non-responsive in
terms of increased Hb level to pharmacological doses of vitamin B6.