Autoimmune Idiopathic Thrombocytopenic Purpura ITP Nicola Davis ITP
Autoimmune Idiopathic Thrombocytopenic Purpura (ITP) Nicola Davis
ITP w Clinical syndrome in which a decreased number of circulating platelets presents as a bleeding tendency, easy bruising, or extravasation of blood from capillaries into skin and mucous membranes
The thrombocytopenia seen in ITP is due to immune destruction of platelets. w Abnormal antibody binds to circulating platelet membranes. w The immunoglobulin coated platelets induce phagocytosis primarily in the spleen. w Thrombocytopenia develops if the bone marrow is unable to increase production of platelets to compensate for the destruction. w
Acute ITP w w w Usually seen in children Peak incidence 3 -5 years M=F Usually occurs ~ 2 weeks following a viral infection Often self limiting
Chronic ITP w w w Usually seen in adults Peak incidence 30 - 40 years Onset in patient >60 years is uncommon F: M = 3: 1 US incidence = 1/10, 000 annually Usually idiopathic but may occur in association with other autoimmune disorders, in patients with CLL and after viral infections
Clinical Features w w w Easy bruising Purpura Epistaxis Menorrhagia Major haemorrhage is rare Splenomegaly is rare
Investigations Diagnosis of exclusion w FBC w • isolated thrombocytopenia • anaemia or neutropenia may indicate other diseases - though may be iron deficiency anaemia from chronic blood loss in chronic ITP w Blood Smear • morphology of platelets is typically normal with varying numbers of large platelets • morphology of RBCs and leukocytes should be normal
w Bone Marrow • normal or increased numbers of megakaryocytes • otherwise normal w Antiplatelet Antibodies • if -ve does not rule out ITP • not essential for the diagnosis of ITP
Treatment w In children: • Treatment depends on bleeding risk • Platelets > 30 can be managed without specific treatment • Platelets < 20 are given oral prednisone 1 mg/kg/day. May also be given high dose IV Ig causing a transient rise in platelet levels.
Treatment w In Adults: • Platelets > 50 have a low risk of haemorrhage and no specific treatment is needed • Platelets < 30 are treated with oral prednisone 1 mg/kg/day. (Improvement seen in a few days) • Platelets < 5 are high risk and should be treated with methylprednisolone and Ig • Platelet transfusions may be used to control bleeding acutely
Surgical Options w Splenectomy • usually results in rapid, complete, lifelong remission in acute ITP • 90% of chronic ITP respond following splenectomy, although ~ 30% of these eventually relapse • There is a lifelong risk of sepsis from encapsulated bacteria following splenectomy so will need immunisation against H. influenzae type B and S. Pneumoniae - boost every 5 years.
Treatment-Resistant ITP w In those patients who do not respond to corticosteriods or splenectomy immunosuppresive drugs may help: • • • azathioprine cyclophosphamide vincristine danazol a non-virilising androgen may also help anti-CD 20 (rituximab)
Prognosis w Children: • >80% with untreated ITP have spontaneous recovery in 2 -8 weeks • Treatment with prednisone and Ig accelerates the increase in platelet count decreasing the chance of serious haemorrhage
Prognosis w Adults: • 60 - 90% of adults have an increased platelet count after treatment with prednisone and Ig • Of those who have a splenectomy ~65% have a sustained response and 10 - 15% have a partial response
Thank You
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