Immune Thrombocytopaenic Purpura (ITP)

Question 1

Define

Answer 1

DEFINITION: syndrome characterised by immune destruction of platelets resulting in bruising or a bleeding tendency

Question 2

Causes

Answer 2

Often IDIOPATHIC

Acute ITP is often seen after viral infection in children

Chronic ITP is more common in adults

ITP may be associated with:

• Infections (e.g. malaria, EBV, HIV)
• Autoimmune diseases (e.g. SLE, thyroid disease)
• Malignancies
• Drugs (e.g. quinine)

Autoantibodies are generated, which bind to platelet membrane proteins (e.g. GlpIIb/IIIa) resulting in thrombocytopaenia

Question 3

Epidemiology

Answer 3

Acute ITP presenting CHILDREN aged 2-7 yrs

Chronic ITP is seen in ADULTS

4 x more common in WOMEN

Question 4

Symptoms

Answer 4

Easy bruising

Mucosal bleeding

Menorrhagia

Epistaxis

Question 5

Signs

Answer 5

Visible petechiae and bruises

Signs of other illness (e.g. infections, wasting, splenomegaly) would suggest that other causes

Question 6

Investigations

Answer 6

Diagnosis of exclusion - exclude:

• Myelodysplasia
• Acute leukaemia
• Marrow infiltration

Bloods

• FBC - low platelets
• Clotting screen - normal PT, APTT and fibrinogen
• Autoantibodies (e.g. antiplatelet antibody)

Blood Film

• To rule out pseudothrombocytopaenia (which is caused by platelets clumping together and giving falsely low counts)

Bone Marrow

• To exclude other pathology