- Acquired thrombocytopenia caused by auto-antibodies against platelet antigens
- Platelets destroyed by spleen secondary to IgG
- Often triggered by viral URTI
- Note different childhood variant
- More severe, M=F
- But 80% spontaneously resolve
Investigations
- Low platelets, normal marrow function
- Note spleen usually normal size
- DDx
- pre-eclampsia, drugs (heparin), viral, chronic liver disease, autoimmune, chronic DIC, lymphoproliferative
Management
- initial management
- Based on platelet count and symptoms
- PLT > 50, asymptomatic
- No Rx, bleeding unlikely even with surgery
- PLT 30-50, asymptomatic
- Follow
- PLT <30, or PLT <50 and symptomatic
- Prednisone 1mg/kg/d 1-3 weeks
- PLT <20
- Admit, IVIG 1g/kg/d for 2 days
- ± transfuse platelets
- IV dexamethasone
- If critical bleeding
- IVIG
- Platelet transfusion
- IV steroids
- Splenectomy is the recommended second line treatment
- Note spontaneous remission is possible, so usually attempt to delay splenectomy for 6-12 months to see if this will occur
- PLT > 50, asymptomatic
- First line
- steroids
- Second line
- Rituximab
- thrombopoietin receptor agonist (TPO-RA)
- IV IG Operative Considerations in ITP
- Indications
- Refractory severe thrombocytopenia
- Needing toxic doses of steroids for remission
- Relapse
- Pregnant and failing conservative measures
- 80-90% curative
- Predictors of success
- Young, Platelets 150 d3, >500 d10
- Most who will respond do so in 10 days
- Predictors of success
- If failure to respond
- Look for accessory spleen
- Especially if absence of asplenic RBC morphology on film (Howell-Jolly bodies)
- Can do RBC scintigraphy (Tc99 TBC scan or Tc99 sulfur colloid scan
- Pre-operative considerations
- Immunisations
- Optimise platelet counts - IVIG, steroids
- Ideally plat count >50 but can still be done with platelets on standby