Hemolytic Anemia and Hemoglobinuria by mohamed Abdelraheem

Acquired Haemolytic Anaemias

• Immune Haemolytic Anaemias:
  • Alloimmune: Haemolytic Disease of the Newborn
    • Results from transplacental transfer of maternal blood group antibodies
    • Interaction of maternal antibodies with incompatible erythrocytes causes haemolysis
    • Can lead to hydrops fetalis, anaemia, jaundice, hepatosplenomegaly, and oedema
  • Autoimmune Haemolytic Anaemia
    • Classified into warm and cold reacting types
    • Warm reacting type: associated with lymphoma, chronic lymphatic leukaemia, systemic lupus erythematosus, and other autoimmune disorders
    • Cold reacting type: associated with Mycoplasma pneumonia, infectious mononucleosis, lymphoproliferative disorders, and paroxysmal cold haemoglobinuria

Immune Haemolytic Anaemias (continued)

• Warm Autoimmune Haemolytic Anaemia
  • Diagnosis: Coombs test
  • Treatment: corticosteroids, splenectomy, immunosuppressive drugs, and rituximab
• Cold Haemagglutinin Disease
  • Agglutinate red cells preferentially at low temperatures (4°C)
  • IGM/C3, C9
  • Reaction occurs in cold parts of the body, leading to intravascular haemolysis, Raynaud's, and other vaso-occlusive phenomena
  • Treatment: keeping the patient warm, treating the underlying cause, and using alkylating agents or anti-CD20 (rituximab)

Non-Immune Acquired Haemolytic Anaemias

• Red cells may be prematurely destroyed through:
  • Increased mechanical stress
  • Acquired defects of the red cell membrane
  • Infections or chemical agents
• Paroxysmal Nocturnal Haemoglobinuria (PNH)
  • Unknown etiology
  • Characterized by chronic intravascular haemolysis with exacerbations associated with haemoglobiniuria and marked thrombotic tendency
  • Due to the presence of an abnormal haemopoietic clone
  • Clinical and haematological features: intravascular haemolysis, venous thrombosis, pancytopenia, and iron deficiency anaemia
  • Treatment: blood transfusion, oral iron, and eculizumab (a humanized antibody against complement C5)
• Microangiopathic Haemolytic Anaemia
  • A group of disorders in which there is intravascular haemolysis and fragmentation of the red cells secondary to disease of the small vessels
  • Causes: DIC, TTP, HUS, prosthetic valve, disseminated cancer, septicaemia, collagen vascular disorders, toxemia of pregnancy, and malignant hypertension
• March Haemoglobinuria
  • Characterized by attacks of haemoglobinuria following strenuous physical exercise
  • A similar picture has been described in practitioners of karate
• Haemolytic Anaemia caused by Chemicals
  • A variety of drugs and chemicals may cause haemolytic anaemia either by direct chemical action on the red cell or by altering red cell metabolism
  • Examples: lead poisoning, thermal cold, hot temperature, and infection

Aplastic Anaemia

• Definition: A gross reduction or absence of haemopoietic precursors in all 3 cell lineages in bone marrow resulting in pancytopenia in peripheral blood
• Etiology:
  • A. Hereditary: Fanconi syndrome, dyskeratosis congenita
  • B. Acquired: chemotherapy, radiotherapy, chronic benzene exposure, drug-induced, post-viral, and idiopathic
• Idiopathic aplastic anaemia constitutes the majority of cases