Paediatrics: Acute immune thrombocytopenia

Acute immune thrombocytopenia

ITP is caused by IgG autoimmune antibody to platelet cell membrane anti-gens leading to platelet destruction in the spleen and liver.

Presentation

·Most present between ages of 2 and 5yrs, but can occur at any age.

·60% have preceding viral infection, e.g. upper respiratory tract infection (URTI).

·Bruising, purpura, petechiae, mucosal bleeding, menorrhagia.

·Intracranial bleeds very rare (< 0.5%); often associated with trauma.

·Physical examination otherwise usually normal, e.g. no splenomegaly.

Investigation

·FBC: platelet count dd, commonly platelet size ‘rise’due to compensatory megakaryocytosis. Otherwise FBC is usually normal.

·Testing for platelet antibodies is not clinically useful.

·Bone marrow in ITP normal, but striking increase in megakaryocytes.

Generally, bone marrow aspirate not indicated if the child is otherwise well, unless concurrent pancytopenia, hepatosplenomegaly, lymphaden-opathy, or abnormally-increased blasts on FBC suggesting alternative diag-nosis, e.g. aplastic anaemia, acute leukaemia, SLE (adolescent girls) or bone marrow failure syndrome.

Management

·Do not treat the platelet count, treat the patient! The aim of treatment is to stop the bleeding not ‘cure’ the disorder, which resolves in its own time. Increases in platelet count will usually be transient, but are usually sufficient to control current bleeding.

·Moderate bleeding can be controlled with tranexamic acid 20–25mg/kg tds for <5 days, provided haematuria is not present.

·Active treatment is required if patient experiencing significant bleeding, mucosal haemorrhage, or haematuria, as all are associated with increased risk of internal bleeding.

·First line therapy: 4mg/kg prednisolone for 4 days and then stop.

·Second line therapy: IV IgG 1g/kg over 2 days if steroids not effective, alternatively can use anti-D antibody (if patient Rh+).

·If bleeding life-threatening or intracranial, give 15–20mL^/kg of platelets, start prednisolone and IV IgG and consider emergency splenectomy.

·Splenectomy for chronic ITP is indicated if disease is not steroid responsive and child over 5yrs.

·For chronic severe ITP, rituximab has been used successfully in young children. Exclude other underlying immunedysregulatory or lymphoproliferative disorders such as X-linked lymphoproliferative (XLP).

·Educate parents regarding ITP, including signs and symptoms that should prompt immediate return to hospital.

·Child can carry on with normal activities, but should avoid contact sports and NSAIDs when platelet count is low.

Prognosis 

Acute ITP in childhood is a self-limiting disorder and >80% spon-taneously remit within 6–8wks. Presentation after 10yrs of age or female sex increases chance of chronic disease.