Immune Mediated Thrombocytopaenia Flashcards
What is Idiopathic Thrombocytopaenic Purpura?
Idiopathic Thrombocytopaenic Purpura is an autoimmune condition which results in the destruction of platelets.
What is the cause of ITP?
When does ITP present?
ITP results from an autoantibody against the surface of platelets. This means that platelets are recognised by splenic macrophages, which ingest and destroy them.
ITP generally manifests itself around 1-4 weeks following a viral infection. The most common linked viruses are EBV and HIV.
How does ITP present?
Generally in a 1-4 year old child:
Previously well
Generalised petechiae and purpura
Bleeding from gums and mucous membranes
Severe thrombocytopaenia (<20) is common
Potential for profound thrombocytopaenia (<10)
Preceding viral illness within 1-4 weeks
Reference: Nelson’s Paediatrics [20th Edition]
What concerns are there with ITP?
Intracranial bleeding (<1%) (especially if evidence of mucosal bleeding (e.g. petechiae in mouth, bleeding in urine/bowels/gums, etc.) which may require active management.
What are the differentials in ITP?
Haemolytic Uraemic Syndrome
Disseminated Intravascular Coagulation
Heparin-induced thrombocytopaenia
Systemic Lupus Erythematosus
Wiskott-Aldrich Syndrome
How is ITP investigated?
Full Blood Count
In acute ITP Hb and WCC should be normal; Hb may be decreased if profuse bleeding.
Blood Film
Platelets may be of normal or increased size owing to higher platelet turnover.
Bone Marrow
Indicated if abnormal WCC
Anti-Nuclear Antibodies
To exclude SLE in adolescents with new-onset ITP
HIV Testing
Consider in high risk groups, e.g. sexually active patients
Source: Nelson’s Paediatrics [18th Edition], p 2083.
How is ITP treated?
Think IITP - Inform, IVIg, Transfuse, Prednisolone
Education and Counselling
This is the mainstay of management.
Intravenous Immunoglobulin
A dose fo 0.8-1g/kg/day for 48 hours might be considered; it raises platelets significantly, but is expensive and can be associated with aseptic meningitis.
Prednisolone
Intravenous anti-D therapy
Might be considered in Rhesus positive patients.
Platelet Transfusion
Platelet transfusion is usually contraindicated - except in the case of life-threatening bleeding - given antibodies bind to transfused platelets just as much as autologous platelets.
Neurosurgical/Surgical Review
May be required in the case of intracranial haemorrhage.
Splenectomy
This is rarely indicated.
Rituximab
Reference: Nelson’s Paediatrics [20th Edition].
What is the prognosis in ITP?
Most should recover platelet count by 1 month. Others by 6 months. Small number (1 in 5) may develop Chronic ITP (>12 months).
Reference: Nelson’s Paediatrics [20th Edition].
