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Hematological System ORGAN SYSTEMS

Hemolytic anemia

Group of disorders characterized by a premature RBC destruction that exceeds the compensatory capacity of the bone marrow to increase RBC production and keep up with the loss.

Group of disorders characterized by a premature RBC destruction that exceeds the compensatory capacity of the bone marrow to increase RBC production and keep up with the loss.


Etiopathogenesis


Classification

  • According to site of RBC destruction:
    • Intravascular (IV) hemolysis: In the circulation
    • Extravascular (EV) hemolysis: Within macrophages in the spleen or liver.
  • According to the location of the abnormality responsible for hemolysis:
    • Intrinsic (intracorpuscular) defects: : Most intrinsic defects are inherited
    • Extrinsic (extracorpuscular) defects: Most extrinsic ones are acquired
Common causes of hemolysis classified by type. | G6PD: glucose-6-phosphate dehydrogenase; CLL: chronic lymphocytic leukemia; NHL: non-Hodgkin lymphoma; SLE: systemic lupus erythematous; TIPS: transjugular intrahepatic portosystemic shunt; TTP: thrombotic thrombocytopenic purpura; HUS: hemolytic uremic syndrome; HELLP: hemolysis, elevated liver enzyme levels, and low platelet levels; DIC: disseminated intravascular coagulation; EV: extravascular: IV: intravascular. | Ruiz, E. F., & Cervantes, M. A. (2015). Diagnostic approach to hemolytic anemias in the adult. Revista brasileira de hematologia e hemoterapia, 37(6), 423–425. https://doi.org/10.1016/j.bjhh.2015.08.008

Presentation


Diagnosis

Presumptive diagnosis:

  • Common findings:
    • Unconjugated hyperbilirubinemia: Clinically evidenced by jaundice
    • RBC destruction: Increased lactate dehydrogenase
    • Compensatory bone marrow response: Reticulocytosis
    • Decreased plasma haptoglobin (marker of RBC destruction)
      • Severe acute intravascular HAs: Haptoglobin-binding capacity reaches its saturation point, and free hemoglobin is filtered by the glomerulus and hemoglobinuria is seen
  • Intravascular hemolysis:
    • Hemoglobinuria
    • Hemosiderinuria (long-term)
  • Extravascular hemolysis:
    • Urobilinogen in urine
    • Absent hemoglobinuria/hemosidenuria

Immune-based tests:

  • Direct antiglobulin test (DAT)
  • Direct Coombs test
  • Immune HAs (DAT positive):
    • Autoantibodies (warm, cold or mixed)
    • Alloimmunization (as in transfusion incompatibility)
    • Drug-related (hemolysis by haptens, autoantibodies or immune complexes)
A simple approach to identify and classify hemolytic anemias. DAT: direct antiglobulin test; HA: hemolytic anemia; PNH: paroxysmal nocturnal hemoglobinuria. | Ruiz, E. F., & Cervantes, M. A. (2015). Diagnostic approach to hemolytic anemias in the adult. Revista brasileira de hematologia e hemoterapia, 37(6), 423–425. https://doi.org/10.1016/j.bjhh.2015.08.008

Peripheral blood smear (PBS):

PBS is a critical step in the evaluation of non-immune HAs (DAT negative). Certain morphological abnormalities of RBCs correlate with different pathologies.
  • Abnormal PBS: If the PBS is abnormal, the family history may identify a congenital HA including disorders of enzymes (G6PD deficiency, pyruvate kinase deficiency) hemoglobin (thalassemia, sickle cell anemia) or of the membrane (hereditary spherocytosis, elliptocytosis). Likewise, traumatic hemolysis (of big or small vessels), infectious (Bartonella, Babesia, Plasmodium) or toxic (exogenous or endogenous) pathologies should be taken into account if there is an abnormal PBS in the absence of family history.
    • Schistocytes: Thrombotic microangiopathies or cardiac prosthetic valves
    • Spherocytes: Hereditary spherocytosis
    • Sickled cells: Sickle cell disease
    • Elliptocytes: Hereditary elliptocytosis
    • Echinocytes: Pyruvate kinase deficiency
    • Heinz bodies: G6PD deficiency
    • Basophilic stipplings: Lead poisoning, thalassemia, and Wilson’s disease
  • Normal PBS:

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