Idiopathic thrombocytopenic purpura

By | 15th May 2012

 

 

Definition:

It is an autoimmune bleeding disorder in which antibodies are formed against platelets causing the destruction and premature removal by monocyte macrophage system. Exact etiology is not known but is associated with some risk factors mentioned below

 

  1. Post infection

 

  1. ITP may follow infection with rubella –HIV-HBV (infectious mononucleosis)

 

  1. Vertical transmission

 

Mother with ITP, her infant also affected because of platelet transport across the placenta.

 

  1. post transfusion

 

Following administration of the platelet antigen positive blood to patient who lacks this specific platelet antigen develops ITP.

  1. Associated with Autoimmune disorders

 

Examples included SLE, lymphoproliferative disorder.

 

Clinical features

·        Acute type occurs in children of 2-6 yrs .appears suddenly following non specific viral infection

·        70 % causes revolve spontaneously within few weeks.

·        Chronic occurs in adults predominantly in female .onset is insidious with relapses and remission.

·        10% of cases resolve by itself.

 

Features

  • Petechial hemorrhages on skin.
  • Epistaxis
  • Bleeding from gums
  • History of bruising in chronic cases
  • Splenomegaly
  • Increases in bleeding after trauma.

 

Investigations

A) Blood examination

  • Platelet count decreased
  • Bleeding time prolonged
  • Clotting time normal
  • Prothrombin time normal or increased
  • Clot retraction poor
  • Capillary fragility is greatly increased(rumple-leede test)

 

B) Bone marrow aspiration

a) Purpose: to diagnose ITP, to rule out leukemia and aplastic anemia.

b) Increased megakaryocytes: With following characteristics

  •  Not surrounded by platelets
  • abnormal in shape
  • single nuclei
  • after vacuoles seen

 

Treatment:

 

General measures

 

  • Patient should avoid trauma, elective surgery, tooth extraction etc.
  • Also avoid unnecessary medications for example aspirin.

 

Corticosteroids

Prednisolone tablet 10-20 mg qti

Dose should be continued until platelet returns to normal then gradually decrease the dose.

 

 

Indications of Splenectomy:

 

Cases that relapse 2-3 times after steroid therapy

Cases not responding to steroid treatment

Platelet count rise quickly following splenectomy and becomes double within 24 hours and …….

 

Immunosuppressive therapy

 

  • Case that not responding to steroid treatment
  • Case when splenectomy failed t increase platelets
  • Drug IV vincristine -1.4 mg for 4-6 weeks

 

IV immunoglobulin

  • In acute crisis
  • Preoperatively in patient requiring surgery.
  • Dose – IV immunoglobulin 400 mg /kg for five consequent days.