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Sideroblastic anemia

Sideroblastic anemia is a rare blood disorders characterized by the bone marrow's inability to manufacture normal red blood cells. Sideroblastic anemias is one of the principal types of iron-utilization anemias that are usually part of a myelodysplastic syndrome, producing a normocytic-normochromic anemia with high RBC distribution width or a microcytic-hypochromic anemia, particularly with increased serum iron, ferritin, and transferrin saturation. Three categories of sideroblastic anemia are: hereditary, acquired or idiopathic.

What is sideroblastic anemia?
Sideroblastic anemia is a rare blood disorders characterized by the bone marrow's inability to manufacture normal red blood cells. Sideroblastic anemias is one of the principal types of iron-utilization anemias that are usually part of a myelodysplastic syndrome, producing a normocytic-normochromic anemia with high RBC distribution width or a microcytic-hypochromic anemia, particularly with increased serum iron, ferritin, and transferrin saturation. Three categories of sideroblastic anemia are: hereditary, acquired or idiopathic.

Hereditary Sideroblastic Anemia is due to a genetic defect; the gene is an X-linked recessive gene. It may manifest in both men and women but is seen more commonly in young males, maternal uncles and cousins. Hereditary sideroblastic anemia generally manifests during the first three decades of life especially during adolescence but it has been diagnosed in patients over seventy.

Acquired sideroblastic anemia is due to prolonged exposure to toxins like alcohol, lead, drugs or nutritional imbalances such as deficiency in folic acid, deficiency in copper or excess zinc. Other causes are due to disease such as inflammatory conditions like rheumatoid arthritis, cancerous conditions such as leukemia, lymphoma; kidney disorders causing uremia; endocrine disorders such as hyperthyroidism; metabolic disorders such as porphyria cutanea tarda. Acquired sideroblastic anemia is usually seen in patients over 65 year of age but it can be present as early as mid to late fifties.

Idiopathic sideroblastic anemia is referred to as myelodysplastic syndrome (MDS). Myelodysplasia is a bone marrow dysfunction disorder which can develop into aplastic anemia requiring bone marrow or stem cell transplantation. Lab findings for acquired/idiopathic sideroblastic anemia: Anemia is usually mild with hemoglobin 10-11.8g/dL Serum iron increased, transferrin iron saturation percentage increased, ferritin increased, transferrin is decreased. TIBC is normal to decreased; serum transferrin receptor is normal to high Mean Corpuscular Volume (MCV) is normal to slightly increased. Mean Corpuscular Hemoglobin and Mean Corpuscular Hemoglobin Concentration are usually normal. Red Cell Distribution Width is increased. White blood cells and platelets are decreased.

What're causes of sideroblastic anemia?
The cause of sideroblastic anemia cannot always be identified, some causes include:

  • Toxins: lead or zinc poisoning
  • Drug-induced: ethanol, isoniazid, chloramphenicol, cycloserine
  • Nutritional: pyridoxine or copper deficiency
  • Genetic: ALA synthase deficiency (X-linked)

    Sideroblastic anemia is also associated with:

    • leukemia
    • lymphoma (cancer of the lymph glands)
    • myeloma (cancer of the bone marrow)
    • rheumatoid arthritis, and other inflammatory diseases

    What're the complications of sideroblastic anemia?

    • Possible complications of sideroblastic anemia include:
    • congestive heart failure
    • diabetes mellitus
    • enlargement of the liver and spleen
    • formation of liver nodules and scar tissue
    • irregular heartbeat
    • recurring inflammation of the sac that surrounds the heart
    • secondary hypopituitarism
    • skin darkening
    • underactivity of the thyroid gland

    What're symptoms of sideroblastic anemia?
    Symptoms of sideroblastic anemia include skin paleness, fatigue, dizziness and enlarged spleen or liver, liver disease, cardiac arrhythmia.

    How is diagnosis of sideroblastic anemia?
    In patients with sideroblastic anemia, the complete blood cell (CBC) count usually reveals anemia, mostly moderate, although severe anemia has been reported. The mean corpuscular volume (MCV) is usually low, with a microcytic picture; however, normocytic, macrocytic and classic dimorphic (normocytic + microcytic) smears are not uncommon. Dimorphic anemia is not specific for sideroblastic anemia and is also seen in combined vitamin B-12 deficiency with iron deficiency and after blood transfusions. Other cell lines may be undisturbed in pure sideroblastic anemia. The peripheral smear may exhibit basophilic stippling in cases of lead poisoning.

    A bone marrow aspirate and biopsy usually has already been done when a physician is faced with the diagnosis of sideroblastic anemia.

    How is treatment of sideroblastic anemia?
    Acquired sideroblastic anemia may be cured when the condition that causes it is treated or removed. If the cause of a patient's anemia cannot be determined, blood transfusions may be necessary. Medications are prescribed to stimulate excretion or excess iron that accumulates as a result of these transfusions. In rare instances, treatment with oral pyridoxine (a B-complex vitamin) benefits patients whose sideroblastic anemia was present at birth. This treatment improves the condition of some patients but does not cure the anemia.

    • Submitted by Health Studies on Mon, 03/15/2010 - 17:51
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