Hemolytic Anemia Types and Causes

Study Notes

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

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

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

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 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)

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

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

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 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)