Haemolytic Anemia Notes

Haemolytic Anemia Evaluation

• Initial Evaluation for Haemolysis:

  • Unconjugated bilirubin: This is bilirubin that has not been processed by the liver; as such, it is not water-soluble and its presence in elevated levels can indicate increased red blood cell destruction.

  • Hemoglobin levels: A complete blood count (CBC) should be performed to assess hemoglobin concentrations, which helps determine if anemia is present and to what extent. Normal hemoglobin values vary based on age and sex, with lower levels indicating anemia.

  • Reticulocyte count: This test measures the percentage of young red blood cells in the blood, indicating the bone marrow's response to the deficiency in red blood cells. An increased reticulocyte count suggests active red blood cell production to compensate for hemolysis.

• Lab Tests to Evaluate Haemolysis:

  • LDH (Lactate Dehydrogenase): Elevated levels in the bloodstream suggest cell damage or destruction, as LDH is released when red blood cells are lysed.

  • FBC (Full Blood Count): Comprehensive assessment of red blood cell indices, including mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH), is critical for diagnosing different types of anemia and identifying underlying abnormalities.

  • Bilirubin levels: It is crucial to measure both total and indirect (unconjugated) bilirubin levels; high levels of the indirect form are often associated with hemolytic conditions.

  • Haptoglobins: A decrease in haptoglobin levels occurs when free hemoglobin is released into the plasma, indicating intravascular hemolysis as haptoglobin binds to hemoglobin to remove it from circulation.

  • Direct Coombs (DAT): This test identifies the presence of antibodies attached to red blood cells, thus helping to distinguish autoimmune hemolytic anemia from other types of hemolytic processes.

Blood Film Findings and Associated Conditions

• Spherocytes:

  • These are small, spherical red blood cells lacking the normal biconcave shape and central pallor, often appearing in hereditary spherocytosis and autoimmune hemolytic anemia.

  • Family history Negative DAT Hereditary spherocytosis: Suggests that the condition is genetic, with spherocytes resulting from defective spectrin or ankyrin proteins in the cell membrane.

  • Positive DAT Autoimmune disease: Indicates that the immune system mistakenly attacks red blood cells, leading to their premature destruction.

• Schistocytes:

  • These are fragmented red blood cells that indicate mechanical damage, often seen in disorders like microangiopathic hemolytic anemia (MAHA) where small blood vessels cause shear stress on blood cells.

  • Mechanical damage: Schistocytes are particularly noted in thrombotic thrombocytopenic purpura (TTP) and hemolytic uremic syndrome (HUS).

  • March haemoglobinuria: This occurs when intense physical exercise causes the release of hemoglobin into the urinary tract without significant hemolysis elsewhere.

• Haemoglobinopathies:

  • Sickle cell anemia: Characterized by abnormal hemoglobin (HbS), causing crescent or sickle-shaped cells that can block capillaries and reduce blood flow.

  • Thalassaemia: A group of inherited blood disorders resulting in abnormal hemoglobin production, leading to target cells and microcytosis due to ineffective erythropoiesis.

• Infection:

  • Certain viral and bacterial infections can lead to hemolytic anemia either through direct destruction of red blood cells or by triggering an immune response that leads to hemolysis.

  • Drugs: Certain medications like penicillin or quinine can induce hemolytic reactions in individuals with marked sensitivity or specific enzyme deficiencies.

  • G-6-PD deficiency: This enzymatic defect makes red blood cells vulnerable to oxidative stress from certain infections, drugs, and foods, leading to hemolytic episodes.

  • Fever: Infections accompanied by fever can provoke hemolysis by increasing metabolic demand and altering red blood cell integrity.

  • Malaria: This parasitic infection results in the destruction of red blood cells by the Plasmodium species, which replicate within and burst the cells.

  • Thick and thin blood films: These diagnostic tools are employed to identify the presence of malaria parasites, enhancing the accuracy of diagnosis.

Red Cell Morphology

• Bite Cells:

  • These red blood cells exhibit portions that appear "bitten out," typically formed when splenic macrophages remove Heinz bodies, which are aggregates of denatured hemoglobin from oxidative damage.

• Blister Cells (Pruse Cells or Pre-keratocytes):

  • Red blood cells displaying a protruding blister-like formation in their membrane, indicating early stages of oxidative damage. Their presence can lead to keratocytes.

• Helmet Cells or Horn Cells (Keratocytes):

  • Characterized by two pointed projections resembling a helmet, keratocytes result from the rupture of blister cells following oxidative damage or trauma.

• Triangle Fragments:

  • These are irregularly shaped fragments of red blood cells that can arise from various forms of blood cell destruction, generally associated with mechanical hemolysis due to blood flow disruptions.