Anemia, sideroblastic

Sideroblastic anemia

Sideroblastic anemia is a form of anemia characterized by the presence of ringed sideroblasts in the bone marrow. These are abnormal nucleated erythroblasts (precursors to red blood cells) with iron-loaded mitochondria arranged in a ring around the nucleus. This condition can be either congenital or acquired and is often associated with ineffective erythropoiesis.

Classification

Sideroblastic anemia can be classified into two main types:

• Congenital sideroblastic anemia - This type is usually due to genetic mutations affecting enzymes involved in heme synthesis or iron-sulfur cluster biogenesis.
• Acquired sideroblastic anemia - This type can be further divided into:

 * Primary acquired sideroblastic anemia - Often associated with myelodysplastic syndromes.
 * Secondary acquired sideroblastic anemia - Can be caused by factors such as alcoholism, lead poisoning, certain medications, and vitamin B6 deficiency.

Pathophysiology

The hallmark of sideroblastic anemia is the presence of ringed sideroblasts. These cells are characterized by the accumulation of iron in the mitochondria due to defective heme synthesis. The iron-laden mitochondria form a ring around the nucleus of the erythroblast, which can be visualized using a Prussian blue stain.

Symptoms

Common symptoms of sideroblastic anemia include:

• Fatigue
• Weakness
• Pallor
• Shortness of breath
• Palpitations

Diagnosis

Diagnosis of sideroblastic anemia typically involves:

• Complete blood count (CBC) - May show microcytic or macrocytic anemia.
• Bone marrow biopsy - Reveals ringed sideroblasts.
• Iron studies - Often show increased serum iron and ferritin levels.
• Genetic testing - For congenital forms.

Treatment

Treatment depends on the underlying cause:

• For congenital forms, pyridoxine (vitamin B6) supplementation may be beneficial.
• For acquired forms, addressing the underlying cause (e.g., discontinuing offending drugs, treating alcoholism) is crucial.
• In some cases, blood transfusions or iron chelation therapy may be necessary.

Prognosis

The prognosis of sideroblastic anemia varies depending on the underlying cause and the effectiveness of treatment. Congenital forms may require lifelong management, while acquired forms may improve with appropriate treatment of the underlying condition.

Related Pages

• Anemia
• Myelodysplastic syndromes
• Erythropoiesis
• Heme synthesis
• Iron metabolism