Specific causes of haemolytic anaemia Flashcards
What is warm autoimmune haemolytic anaemia?
A form of Coombs positive haemolytic anaemia in which the antibody binds best at warm temperature (37 degrees celsius)
What are the causes of warm autoimmune haemolytic anaemia?
Idiopathic
Lymphoproliferative neoplasms (e.g. chronic lymphocytic leukaemia and lymphoma)
Drugs including methyldopa
Systemic lupus erythematosus (SLE)
Pathophysiology of warm autoimmune haemolytic anaemia?
Itis an IgG mediated extravascular haemolytic disease, in this the spleen identifies cells for splenic phagocytosis
Management of warm autoimmune haemolytic anaemia?
First line: prednisolone 1mg/kg/day
Transfusion may be required (in severe cases
If no response with steroids:
- Immunosuppression e.g azathioprine, IV immunoglobulin, rituximab)
- Splenectomy
What is cold autoimmune haemolytic anaemia?
A form of Coombs-positive haemolytic anaemia in which the antibody binds mostly at cold temperatures (4 degrees celsius).
What are the causes of cold autoimmune haemolytic anaemia?
Idiopathic
Post infectious haemolytic anaemia – occur 2-3 weeks after infection (e.g. Epstein-Barr virus, mycoplasma).
Lymphoproliferative disorders
Pathophysiology of cold autoimmune haemolytic anaemia?
IgM-mediated disease, IgM fixes to the complement causing intravascular haemolysis.
Includes cold agglutinin disease
The IgM agglutinates also cause the hands and feet to become blue in cold conditions (acrocyanosis)
Management of cold autoimmune haemolytic anaemia?
Treatment is supportive - keep patient warm and if required transfuse blood using a blood warmer.
Exclude any underlying treatable cause
No proven benefit with steroids
Resistant cases may respond to alkylator therapy (e.g. low dose cyclophosphamide or rituximab)
What is Coombs-negative haemolytic anaemia?
Acquired haemolytic anaemias that are Coombs-negative are a large group of inherited disorders, includes:
- Microangiopathic haemolytic anaemia
- Paroxysmal nocturnal haemoglobinuria (PNH)
- Physical lysis of red blood cells (e.g. malaria)
- Haemolytic uraemic syndrome (HUS)
often caused by E.Coli
What is microangiopathic haemolytic anaemia?
Intravascular haemolytic disorder caused by physical lysis of red cells by deposited fibrin strands in capillary bed, leading to presence of schistocytes (fragments of RBC’s) and fragmentation on blood film
Aetiology of microangiopathic haemolytic anaemia?
Disseminated intravascular coagulation
Haemolytic uraemic syndrome
Thrombotic thrombocytopenic purpura
Malignant hypertension
Severe pre-eclampsia
What is paroxsymal nocturnal haemoglobinuria?
Rare acquired stem cell disorder of unknown aetiology.
Features of paroxysmal nocturnal haemoglobinuria?
Patients present in early adulthood with:
- Nocturnal episodes of intravascular haemolysis (unknown why this occurs at night)
- Haemoglobinuria (free haemoglobin in urine)
- Leukopenia (low WBC count)
- Thrombocytopenia (low platelet count)
- Occasionally pancytopenia (deficiency of RBC, WBC and platelets)
What can cause physical lysis of red blood cells?
Falciparum malaria and babesiosis - diseases in which the parasite grows in the red cell cytoplasm.
Patients with prosthetic heart valves
