Etiology, Pathogenesis, Hematologic Indices, and Peripheral Blood Characteristics of Acquired Hemolytic Anemia

Acquired hemolytic anemia is a condition where premature destruction of red blood cells (RBCs) leads to anemia. It can be caused by various factors, including autoimmune disorders, infections, medications, and mechanical damage.

Etiology

The causes of acquired hemolytic anemia can be broadly classified into immune and non-immune mechanisms:

• Immune-mediated hemolysis: Autoimmune hemolytic anemia (AIHA), drug-induced hemolysis, alloimmune hemolysis.
• Non-immune hemolysis: Microangiopathic hemolytic anemia (MAHA), infections like malaria, enzymatic defects.

Pathogenesis

Destruction of RBCs occurs through various mechanisms:

• Complement-mediated lysis
• Phagocytosis by macrophages
• Mechanical fragmentation due to vascular stress

Hematologic Indices Used to Assess Hemolytic Anemia

Several hematologic indices help in diagnosing hemolytic anemia:

• Reticulocyte count: Increased due to compensatory erythropoiesis.
• Haptoglobin levels: Decreased due to hemoglobin binding.
• Lactate dehydrogenase (LDH): Elevated due to RBC destruction.
• Direct and indirect Coombs test: Helps in diagnosing autoimmune causes.

Peripheral Blood Characteristics

Typical peripheral blood smear findings include:

• Schistocytes (fragmented RBCs)
• Spherocytes
• Nucleated RBCs
• Polychromasia indicating active erythropoiesis

Conclusion

Acquired hemolytic anemia is a complex disorder with diverse etiologies. Understanding its pathogenesis and hematologic indices aids in accurate diagnosis and effective management.