Sideroblastic Anemia Overview

Sideroblastic Anemia

• Siderocytes: Mature red blood cells containing iron granules (Pappenheimer bodies), considered abnormal.
• Sideroblasts: Immature nucleated red blood cells in the bone marrow containing small amounts of iron in the cytoplasm, considered normal.
• Sideroblastic Anemia: Characterized by iron accumulation within mitochondria of immature red blood cells in the bone marrow. Iron forms a ring around the nucleus in these cells, called ringed sideroblasts, considered abnormal.

Types of Sideroblastic Anemia

• Primary Sideroblastic Anemia: Cause unknown, not reversible.
• Secondary Sideroblastic Anemia: Commonly due to alcohol, anti-tuberculosis drugs, and lead poisoning.
• Alcohol and anti-tuberculosis drugs: Inhibit vitamin B6 (pyridoxine).
• Lead poisoning: Inhibits multiple steps in the protoporphyrin pathway.

Lead Poisoning

• Lead poisoning: Inhaled or ingested lead results in abnormal lead levels.
• Symptoms: Neurologic issues and lead lines on the gums.
• Treatment: Chelation therapy using EDTA.

ACD Pathogenesis

• Lactoferrin: Iron-binding protein in the granules of neutrophils, binds iron with higher affinity than transferrin.
• Infection or inflammation: Neutrophils release lactoferrin into the plasma, which scavenges available iron.
• Lactoferrin binds to: Macrophages and liver cells (due to their lactoferrin receptors).

Cytokines

• Cytokines: Produced by macrophages during inflammation.
• Effect of cytokines: Contribute to anemia of chronic disease by inhibiting erythropoiesis.

Lab Diagnosis

• Blood findings:
  • Early stage: Normocytic, hypochromic.
  • Late stage: Hypochromic, microcytic.
  • Low serum iron, low TIBC, normal or high serum ferritin.
  • Increased reticulocyte count.
  • Decreased hemoglobin and hematocrit.
• Leukocytosis: Elevated white blood cell count.
• Abundant storage of iron in macrophages: Observed using Prussian blue staining.