Basophilic stippling is marked and target cells are common. The mean cell volume is commonly decreased (i.e., a microcytic anemia), but it may also be normal or even high. The RDW is increased with the red blood cell histogram shifted to the left. Leukocytes and platelets are normal. Bone marrow shows erythroid hyperplasia with a maturation arrest.In excess of 40% of the developing erythrocytes are ringed sideroblasts. Serum iron, percentage saturation and ferritin are increased. The total iron-binding capacity of the cells is normal to decreased. Stainable marrow hemosiderin is increased. Classification
Sideroblastic anemia is typically divided into subtypes based on its cause. Hereditary or congenital sideroblastic anemia may be X-linked or autosomal.GLRX5 has also been implicated. Acquired, or secondary, sideroblastic anemia develops after birth and is divided according to its cause. Laboratory findings
Serum Iron: high
increased ferritin levels
decreased total iron-binding capacity
high transferrin saturation
Hematocrit of about 20-30%
The mean corpuscular volume or MCV is usually normal or low for congenital causes of sideroblastic anemia but normal or high for acquired forms. With lead poisoning, see coarse basophilic stippling of red blood cells on peripheral blood smear
Specific test: Prussian blue stain of RBC in marrow shows ringed sideroblasts. Prussian blue staining involves a non-enzymatic reaction of ferrous iron with ferrocyanide forming ferric-ferrocyanide, which is blue in color. A counterstain may be used to provide better visualization. Treatment
Occasionally, the anemia is so severe that support with transfusion is required. These patients usually do not respond to erythropoietin therapy.
Sideroblastic anemia, or sideroachrestic anemia, is a form of anemia in which the bone marrow produces ringed sideroblasts rather than healthy red blood cells (erythrocytes). In sideroblastic anemia, the body has iron available but cannot incorporate it into hemoglobin, which red blood cells need in order to transport oxygen efficiently. The disorder may be caused either by a genetic disorder or indirectly as part of myelodysplastic syndrome, which can develop into hematological malignancies (especially acute myeloid leukemia). Sideroblasts (sidero- + -blast) are nucleated erythroblasts (precursors to mature red blood cells) with granules of iron accumulated in the mitochondria surrounding the nucleus. Normally, sideroblasts are present in the bone marrow, and enter the circulation after maturing into a normal erythrocyte. The presence of sideroblasts per se does not define sideroblastic anemia. Only the finding of ring (or ringed) sideroblasts characterizes sideroblastic anemia. Ring sideroblasts are named so because iron-laden mitochondria form a ring around the nucleus. It is a subtype of basophilic granules of the erythrocyte, but which can only be seen in bone marrow. To count a cell as a ring sideroblast, the ring must encircle a third or more of the nucleus and contain five or more iron granules, according to the 2008 WHO classification of the tumors of the hematopoietic and lymphoid tissues.