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HAEMOLYTIC ANAEMIA
Rahul RantaRoll No.1168
DEFINITION
1) Premature destruction of red cells and a shortened red cell life span below normal 120 days
2) Elevated erythropoietin levels and a compensatory increase in erythropoiesis
3) Accumulation of hemoglobin degradation products released by red cell breakdown derived from haemoglobin
CLASSIFICATION
ACQUIRED HAEMOLYTIC ANAEMIA
IMMUNE HAEMOLYTIC ANAEMIA
These can be subdivided into:a) Autoimmuneb) Alloimmunec) Drug-induced
AUTOIMMUNE HAEMOLYTIC ANAEMIA
warm antibodies bind to RBC most avidly at 370C
cold antibodies bind best below 320C
Caused by antibodies produced by patient’s own immune system
Classified according to thermal properties of antibodies:
Warm AIHA:
Antibody usually IgG, but may be IgM or IgA CAUSES –1. alternation in membrane surface antigen2. Or abnormal response of B lymphocyte
causing auto antibody formation May be primary or secondary – autoimmune disorders, HIV, chronic lymphocytic leukaemia (CLL), non-Hodgkin's lymphoma (NHL)
Most common type
Incidence:
Occurs in either sex but female preponderance reported
Occurs in all ages
Higher incidence noted in patients > 45 years
Clinical Features:
Hemolytic anaemia of varying severity Tends to remit and relapse Haemoglobinurea rare Jaundice Splenomegaly
Laboratory Features:
Variable anaemia Blood film: polychromasia, microspherocytes Severe cases: nucleated RBCs, RBC fragments Mild neutrophilia, normal platelet count Evan’s syndrome: association with ITP Bone marrow: erythroid hyperplasia;
underlying lymphoproliferative disorder Unconjugated hyperbilirubinaemia Haptoglobin levels low Urinary urobilinogen usually increased;
haemoglobinuria uncommon
Serological Features
Direct antiglobulin test (DAT; Coomb's test) usually positive
Indirect antiglobulin test positive RBC may be coated with
1) IgG alone2) IgG and complement3) complement only Rarely anti-IgA and anti-IgM encountered
Treatment:
Corticosteroids – 1mg/kg daily till Hb stabilizes Transfusion Splenectomy:
1) patients who fail to respond to steroids
Immunosuppressive Drugs : severe cases Others:
1) plasmapheresis
2) Intravenous immunoglobulin (IVIG) 1g/kg daily for 2days
3) danazol in chronic haemolytic anaemia
Cold AIHA:
• Two major types of cold antibody: 1) Cold agglutinins
2) Donath-Landsteiner antibodies Causes immediate intravascular
destruction of sensitized RBCs by complement-mediated mechanisms or sequestration by liver (C3 coated RBCs preferentially removed here)
Cold Agglutinins:
IgM autoantibodies that agglutinate RBCs optimally between 0 to 50C. Complement fixation occurs at higher temperatures
Primary - Cold Haemagglutinin Disease (CHAD) or secondary (usually due to infections)
Occurs in male mostly
Pathogenesis:
Specificity usually against I/i antigens
Bind red cells in peripheral circulation impeding capillary flow, producing acrocyanosis
Clinical Features:
Chronic haemolysis; episodes of acute haemolysis can occur on chilling
Acrocyanosis frequent; skin ulceration and necrosis uncommon
Mild jaundice and splenomegaly Secondary cases e.g. Mycoplasma, self-
limited
Laboratory Features:
Anaemia- mild to moderate Blood film:a) agglutination, or rouleaxb) spherocytosis less marked than warm AIHA
DAT +ve: complement only Anti-I: idiopathic disease, mycoplasma,
some lymphomas Anti-i: infectious mononucleosis,
lymphomas
Treatment:
Keep patient warm Treat underlying cause Alkylating agents: chlorambucil Splenectomy and steroids generally not
helpful Plasmapheresis- temporary relief Transfusion- washed packed cells in
severe cases
Paroxysmal Cold Haemoglobinuria
Rare form Characterized by recurrent haemolysis
following exposure to cold common due to association with syphilis Antibodies usually IgG with specificity for
P antigen Biphasic:a) binds to red cells at low temperatures,b) lysis with complement occurs at 37C
Drug-induced Haemolytic Anaemia
May cause immune haemolytic anaemia by three different mechanisms:
Neoantigen type e.g. Quinidine immune complex mechanism Autoimmune mechanism e.g. -
Methyldopa Drug adsorption mechanism e.g.
Penicillin Hapten mechanism
Non-immune haemolytic anaemias:
Paroxysmal nocturnal haemoglobinuria (PNH)
Red cell fragmentation syndromes March haemoglobinuria Infections Chemical and physical agents Secondary haemolytic anaemia
Paroxysmal nocturnal haemoglobinuria (PNH)
Acquired haemopoietic stem cell disorder Characterized by increased sensitivity of red cells to
haemolysis by complement
Pathogenesis:
Arise as a clonal abnormality of stem cells Disorder a consequence of somatic mutations
in synthesis of the glycosylphosphatidylinositol (GPI) anchor
Results in deficiencies of several GPI-anchored membrane proteins –
1) decay accelerating factor (DAF),2) membrane inhibitor of reactive lysis (MIRL),3) acetylcholine esterase,4) leukocyte alkaline phosphatase (LAP) These proteins involved in complement
degradation
Clinical Features:
Haemoglobinuria occurs intermittently Nocturnal haemoglobinuria uncommon Chronic haemolytic anaemia which may
be severe Iron deficiency due to loss in urine Bleeding may occur secondary to
thrombocytopenia Thrombosis a prominent feature
Laboratory Features:
Pancytopenia Anaemia may be severe Macrocytosis may be present due to mild
reticulocytosis Hypochromic, microcytic due to iron
deficiency Marrow: erythroid hyperplasia; may be
aplastic Urine: haemosiderinuria constant feature
Treatment:
Transfusion Oral iron Folate supplements Steroids may be of benefit Anticoagulation for thrombotic
complications
Red Cell Fragmentation Syndromes
Microangiopathic haemolytic anaemia (MAHA) Intravascular haemolysis Red cells adhere to fibrin and are fragmented by force of
blood flow in abnormal arterioles. Underlying disorders: adenocarcinomas Complications of pregnancy: a) Preeclampsia, eclampsia, Haemolysis, Elevated Liver enzymes, Low Platelets
(HELLP) Disseminated Intravascular Coagulation (DIC) Thrombotic Thrombocytopenic Purpura (TTP)/
Haemolytic Uraemic Syndrome (HUS) Malignant hypertension
Laboratory Findings:
Blood film:1) schistocytes prominent,2) spherocytes, 3) reticulocytes,4) normoblasts Thrombocytopenia Coagulopathy in DIC
Traumatic cardiac haemolytic anaemia
Seen in patients with1) prosthetic heart valves, 2) cardiac valvular disorders esp. severe aortic
stenosis Due to1) physical damage of red cells from turbulence 2) high shear stresses Anaemia usually mild