Treatment of ITP

No need to treat mild compensated ITP (>30 x 109/L) unless haemorrhagic manifestations. Keep under regular review and advise urgent FBC if haemorrhagic manifestations. Most children do not require treatment— but those in whom chronic ITP develops are treated in the same way as adults. 90% of children eventually recover completely. Aim of therapy of adult ITP is to achieve an improved (preferably normal) platelet count without need for long term maintenance therapy.

Prednisolone

• First-line therapy for most patients.

• Probably 5 platelet antibody production and interferes with phagocytosis.

• Dose is 1mg/kg/d PO, maintained for at 2 weeks.

• Up to 75% patients will respond but only 15% CR. Note: magnitude and speed of response correlates with long term prognosis.

• Once patient has responded, taper prednisolone dose over several months.

• Some patients will maintain an adequate platelet count (>30 x 109/L) on discontinuation of steroids or on a low maintenance dose.

• Most adults relapse on tapering the prednisolone dose and require other therapy.

IVIg

• Action: blockade of phagocytes and possible anti-idiotype effect.

• Most ITP patients will have significant platelet rise following administration of 2g/kg over 5d.

• Effect often rapid (within 4d) but usually transient and lasts ~3 weeks (may be prolonged in a minority).

• Increment may be maintained with boosters of 0.4g—1g/kg.

• Relatively non-toxic but expensive.

• Useful in patients

- refractory to other treatments.

- who require an urgent increment for surgery and in pregnancy. Splenectomy

• The only proven curative therapy for ITP (spleen is major site of platelet destruction). Usual pre- and post-splenectomy care (ffl p582). 389

• Indium labelled platelet scan appears to be the only test able to predict those patients who will benefit.

• Consider for patients

- who fail to respond to prednisolone.

- requiring prednisolone >10mg/d to maintain acceptable platelet count.

- who have unacceptable side effects with lower maintenance dose.

• 60-80% of patients achieve at least a partial response to splenectomy.

• A brisk rise in platelet count in the immediate post-operative period is a good prognostic sign.

Immunosuppressive agents

• Act through inhibition of antibody production.

• Effect takes at least 2 weeks (may be up to 3 months).

• May be useful in patients

- who have failed to achieve an adequate response to splenectomy.

- in whom splenectomy is contraindicated.

- in whom an unacceptably high dose of prednisolone is necessary to maintain a 'safe' platelet count.

• Effective in up to 25% refractory patients.

• Azathioprine is the most widely used agent in the UK (max 150mg/d). (maintain neutrophil count >1.0 x 109/L and platelet count >30 x 109/L.

• May be used with prednisolone to obtain an acceptable platelet count and minimise the toxicity of each agent.

• Cyclophosphamide and vincristine are alternatives.

• Long term therapy carries risk of serious toxicity including MDS and 2° leukaemias with azathioprine and cyclophosphamide.

Danazol

• May be used as alternative to prednisolone or in combination.

• Normal dose 400-800mg/d for 1-3 months tapering to 50-200mg/d.

• Side effects: virilisation, weight gain and hepatotoxicity.

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