INTRODUCTION TO HEMOLYSIS
Hemolysis (Hem=blood, Lysis= breakdown) is the process of breakdown of red blood cell in which hemoglobin is release with in cell into the plasma.
TYPE OF HEMOLYSIS
1. Physiological hemolysis: Normal rate erythropoiesis + 120 days life = Normal destruction
2. Pathological hemolysis: Raised rate of erythropoiesis + >30 days life = Raised RBC destruction
PHYSIOLOGICAL HEMOLYSIS
○ Normal red blood cell destroyed after completion of their life span (90-120 days).
○ About 1% of total body RBC is destroyed and 1% issynthesize per day.
○ Erythrocyte aging is characterized by a decline in certaincellular enzyme systems.
○ This lead to decreased ATP and loss of reducing system.
○ Free radicles will oxidize the membrane proteins, lipidsand hemoglobin.
○ Resulting loss of ability of cell deformability, shape and membrane integrity.
○ Aged erythrocyte is destroyed in spleen due to low Oxygen supply lead to low glycolysis that favor to cell destruction.
○ Secondly IgG antibodies accumulate on erythrocyte cell surface. Splenic macrophages have receptor for IgG that enhanced recognition of aged cells.
○ Exposure of outlet phosphotidyle serine of erythrocytes membrane is another signal for aged erythrocytes recognition.
○ Most of the aged erythrocytes (90%) breakdown take place in spleen called extravascular hemolysis.
○ Due to sever trauma to RBCs that damages the structural integrity lead to some erythrocytes Lysis (10%) with in vassals called intravascular hemolysis.
○ Free hemoglobin in blood is transported by heptogloininto splenic macrophages.
○ Or free Hemoglobin may dissociate into heme and globin. Heme is transported by hemopexin and globin by haptoglobin into splenic macrophages.
PATHOLOGICAL HEMOLYSIS
○ Pathological hemolysis is the process of mature or premature red cell destruction before their life span hasbeen completed.
○ In pathological hemolysis the rete of erythropoiesis is increased according to the rate of hemolysis.
○ In pathological hemolysis RBC destroyed before 90 days of age.
○ Bone marrow can increased production of RBC 4 to 6 times on the basis of demand.
○ Bone marrow compensate when RBC Lysis between the age of 31 to 90 days of RBC.
○ A condition in which hemolysis is with in compensatory phenomena is called hemolytic disease such as beta thalassemia trait, alpha thalassemia trait etc.
○ A clinical condition in which RBC half life become less than 30 days lead to anemia called hemolytic anemia.
○ Hemolytic anemia may due to extravascular and intravascular.
CLINICAL FINDINGS
○ Pallor of mucous membranes
○ Mild jaundice (increased indirect bilirubin)
○ Splenomegaly (due to hypersplenism)
○ Bilirubinuria (bilirubin in urine)
○ Gall stones in chronic hemolytic anima
• Rarely present with B12 and folate deficiency
LAB FINDINGS
1. Lab findings due to increased red cell destruction
» Extravascular Hemolysis:
○ Increased unconjugated bilirubin level (Jaundice)
○ Increased urobilinogen in urine
○ Peripheral blood film reveals marked polychromasia with spherocytosis.
○ Splenomegaly
2. Lab findings due to increased red cell destruction
» Intravascular Hemolysis:
○ Increased unconjugated bilirubin level (Jaundice)
○ Hemoglobinemia
○ Decreased Haptoglobin and hemopexin levels
○ Hemoglobinuria
○ Hemosidrinuria
○ Peripheral blood film reveals marked fragmentation, polychromasia and spherocytosis.
○ Increased methemalbuminemia and Serum LDH level
3. Lab findings due to increased red cell production
» Intra and extravascular Hemolysis:
○ Reticulocytosis
○ Erythroid hyperplasia on bone marrow examination
4. Lab findings to diagnose type of hemolytic anemia
○ Coombs test (anti-human-gammaglobulin test) to differentiate immune & immune hemolytic anemia
○ Hemoglobin electrophoresis for hemoglobinopathes
○ G6PD detection for enzymopathes (G6PD deficiency anemia)
○ Osmotic fragility test for membranopathes (HS diagnosis)
○ CD55 and CD59 test for PNH diagnosis
