Idiopathic Thrombocytopenic Purpura

Idiopathic thrombocytopenic purpura (ITP) is a condition characterised by idiopathic (spontaneous) thrombocytopenia (low platelet count) causing a purpuric rash (non-blanching rash).

ITP is caused by a type II hypersensitivity reaction. It is caused by the production of antibodies that target and destroy platelets. This can happen spontaneously, or it can be triggered by something, such as a viral infection.

TOM TIP: ITP is worth remembering as it is a key differential diagnosis of a non-blanching rash.



Idiopathic thrombocytopenic purpura usually present in children under 10 years old. Often there is a history of a recent viral illness. The onset of symptoms occurs over 24 – 48 hours:

  • Bleeding, for example from the gums, epistaxis or menorrhagia
  • Bruising
  • Petechial or purpuric rash, caused by bleeding under the skin

TOM TIP: Petechiae are pin-prick spots (around 1mm) of bleeding under the skin. Purpura are larger (3 – 10mm) spots of bleeding under the skin. When a large area of blood is collected (more than 10 mm), this is called ecchymoses. These are all non-blanching lesions.



The condition can be confirmed by doing an urgent full blood count for the platelet count. Other values on the FBC should be normal. Other causes of a low platelet count should be excluded, for example heparin induced thrombocytopenia and leukaemia.

The severity and management depends on how low the platelet count falls. Usually no treatment is required and patients are monitored until the platelets return to normal. Around 70% of patients will remit spontaneously within 3 months.

Treatment may be required if the patient is actively bleeding or severe thrombocytopenia (platelets below 10):

  • Prednisolone
  • IV immunoglobulins
  • Blood transfusions if required
  • Platelet transfusions only work temporarily

Platelet transfusions only work temporarily because the antibodies against platelets will begin destroying the transfused platelets as soon as they are infused.

Some key education and advice is necessary:

  • Avoid contact sports
  • Avoid intramuscular injections and procedures such as lumbar punctures
  • Avoid NSAIDs, aspirin and blood thinning medications
  • Advice on managing nosebleeds
  • Seek help after any injury that may cause internal bleeding, for example car accidents or head injuries



  • Chronic ITP
  • Anaemia
  • Intracranial and subarachnoid haemorrhage
  • Gastrointestinal bleeding


Last updated January 2020