Hemolytic Anemia Types and Causes

Definition and Classification

• Hemolytic anemia is a type of anemia characterized by the premature destruction of red blood cells (RBCs)
• Classified into two main categories:
  • Intrinsic hemolytic anemia: defects within the RBCs themselves
  • Extrinsic hemolytic anemia: destruction of RBCs due to external factors

Causes of Intrinsic Hemolytic Anemia

• Genetic defects:
  • Hereditary spherocytosis: abnormal RBC shape and membrane structure
  • Hereditary elliptocytosis: abnormal RBC shape
  • Pyruvate kinase deficiency: enzyme deficiency affecting RBC energy metabolism
• Acquired defects:
  • Paroxysmal nocturnal hemoglobinuria (PNH): abnormal RBC membrane protein
  • G6PD deficiency: enzyme deficiency affecting RBC antioxidant defenses

Causes of Extrinsic Hemolytic Anemia

• Autoimmune hemolytic anemia (AIHA): production of antibodies against RBCs
  • Warm AIHA: IgG antibodies bind to RBCs at body temperature
  • Cold AIHA: IgM antibodies bind to RBCs at low temperatures
• Infections:
  • Malaria: parasite infection and destruction of RBCs
  • Babesiosis: parasite infection and destruction of RBCs
• Mechanical trauma:
  • Microangiopathic hemolytic anemia: RBC destruction due to abnormal blood flow and small vessel obstruction
• Toxicity:
  • Snake venom: hemolytic toxins in some snake venoms
  • Chemicals: certain chemicals, such as lead, can cause RBC destruction

Clinical Features and Diagnosis

• Symptoms: fatigue, weakness, pale skin, jaundice, dark urine
• Laboratory findings:
  • Anemia: low RBC count, hemoglobin, and hematocrit
  • Reticulocytosis: increased immature RBCs
  • Bilirubinemia: increased bilirubin levels
  • Direct Coombs' test: detects antibodies bound to RBCs
• Diagnostic tests:
  • Blood smear: examination of RBC morphology
  • Bone marrow biopsy: examination of bone marrow cellularity and morphology

Treatment and Management

• Treatment depends on the underlying cause
• Supportive care:
  • Blood transfusions
  • Folic acid supplementation
• Immunotherapy:
  • Corticosteroids
  • Rituximab (for AIHA)
• Splenectomy: surgical removal of the spleen (for hereditary spherocytosis and other forms of hemolytic anemia)

Definition and Classification

• Hemolytic anemia is characterized by the premature destruction of red blood cells (RBCs)
• Classified into two main categories: intrinsic and extrinsic hemolytic anemia

Intrinsic Hemolytic Anemia

• Caused by genetic defects, such as:
  • Hereditary spherocytosis: abnormal RBC shape and membrane structure
  • Hereditary elliptocytosis: abnormal RBC shape
  • Pyruvate kinase deficiency: enzyme deficiency affecting RBC energy metabolism
• Caused by acquired defects, such as:
  • Paroxysmal nocturnal hemoglobinuria (PNH): abnormal RBC membrane protein
  • G6PD deficiency: enzyme deficiency affecting RBC antioxidant defenses

Extrinsic Hemolytic Anemia

• Caused by autoimmune hemolytic anemia (AIHA), including:
  • Warm AIHA: IgG antibodies bind to RBCs at body temperature
  • Cold AIHA: IgM antibodies bind to RBCs at low temperatures
• Caused by infections, such as:
  • Malaria: parasite infection and destruction of RBCs
  • Babesiosis: parasite infection and destruction of RBCs
• Caused by mechanical trauma, such as:
  • Microangiopathic hemolytic anemia: RBC destruction due to abnormal blood flow and small vessel obstruction
• Caused by toxicity, such as:
  • Snake venom: hemolytic toxins in some snake venoms
  • Chemicals: certain chemicals, such as lead, can cause RBC destruction

Clinical Features and Diagnosis

• Symptoms: fatigue, weakness, pale skin, jaundice, and dark urine
• Laboratory findings, including:
  • Anemia: low RBC count, hemoglobin, and hematocrit
  • Reticulocytosis: increased immature RBCs
  • Bilirubinemia: increased bilirubin levels
  • Direct Coombs' test: detects antibodies bound to RBCs
• Diagnostic tests, including:
  • Blood smear: examination of RBC morphology
  • Bone marrow biopsy: examination of bone marrow cellularity and morphology

Treatment and Management

• Treatment depends on the underlying cause
• Supportive care, including:
  • Blood transfusions
  • Folic acid supplementation
• Immunotherapy, including:
  • Corticosteroids
  • Rituximab (for AIHA)
• Surgical intervention, including:
  • Splenectomy: surgical removal of the spleen (for hereditary spherocytosis and other forms of hemolytic anemia)

Learn about the different types of hemolytic anemia, including intrinsic and extrinsic, and their causes such as genetic defects and external factors.