HEMOLYTIC DESORDERS
Red Cell Turnover and Life Span 2.5 million red cells are removed from the circulation every second. BM produces 200 billion new red cells (reticulocytes) each day. These cell survived for 120 days before they are removed by the RES (macrophage-monocyte system) ( BM, liver, spleen)Definition HA is a decrease in the total number of circulating erythrocytes that is caused by the premature destruction or removal of red cells from the circulation. Anaemia will result only if the rate of RBCdestruction exceed the BM response (uncompensation).
HEMOLYTIC ANAEMIA(HA)
CLASSIFICATION1.Acute versus chronic . 3.Intra-vascular versus extra-vascular. 4.Intra-corpuscular versus extra-corpuscular.
2.Acquired versus congenital.
Clinical featuresChronic congenital HA
AnaemiaJaundice CrisisSplenomegalyGall stonesLeg ulcers Skeletal abnormalities
Acute (Acquired) HA
sudden pallor JaundiceTachycardiaAching pain,headache,malaise, vomiting, shaking chills and fever.Manifestation of the underlying disease.
Destruction of RBCs within the intravascular space requires a considerable amount of structural damage to the RBC membrane. The following are examples;●Direct trauma, as in bongo drummers and march hemoglobinuria (runners' or foot-strike hemolysis)●Shear stress, as in defective mechanical heart valves●Heat damage, as in thermal burns●Complement-induced lysis, as in paroxysmal cold hemoglobinuria●Osmotic lysis following infusion of hypotonic solutions●Lysis from bacterial toxins (eg, clostridial sepsis)●Lysis from exposure to high concentrations of copper
Laboratory manifestation
I. signs of excessive RBC destruction:Decrease RBC life span Increase catabolism of heme. indirect hyperbilirubinaemia. increase rate of bilirubin production. increase rate of urobilinogen production increase LDH activity Absence of serum haptoglobin
II. signs of accelerated erythropoiesis
Blood Reticulocytosis (polychromasia in the blood film). Macrosytosis. Normoblastaemia . Leukocytosis and thrombocytosis Bone marrow Erythroid hyperplasia. Ferrokinetics: increase plasma iron turnover . increase erythrocyte iron turnoverDifferential diagnosis The DD III.Lab tests useful in
Morphology(blood film findings) Spherocytes are small, dark red cells that suggest autoimmune haemolysis or hereditary spherocytosis.• Sickle cells suggest sickle-cell disease.• Red cell fragments indicate microangiopathic haemolysis.• Bite cells (normal-sized red cells that look as if they have been partially eaten) suggest oxidative haemolysis Coomb’s test (Direct anti-human globulin-DAT) . Osmotic fragility test Auto-hemolysis test.Hb-electorphoresis test . Screening for G6PD deficiencySickling test .Investigation results indicatingactive haemolysis
Direct antiglobulin testIndirect antiglobulin test