Immune thrombocytopenic purpura
Background
- Acquired autoimmune disease resulting in destruction of platelets
- Because circulating platelets are functional, life-threatening bleeding only once platelet count <10K
Types
- Acute
- More common among younger children
- Affects men/women equally
- Resolves in 1-2 months
- Chronic
- Lasts > 3 months
- More common in adults and women
- Rarely remits spontaneously or with treatment
- More likely to have an underlying disease or autoimmune disorder (e.g. SLE)
Clinical Features
Differential Diagnosis
Thrombocytopenia
Decreased production
- Marrow infiltration (tumor or infection)
- Viral infections (rubella, HIV)
- Marrow suppression (commonly chemotherapy or radiation)
- Congenital thrombocytopenia
- Fanconi anemia
- Alport syndrome
- Bernand Soulier
- Vitamin B12 and/or folate deficiency
Increased platelet destruction or use
- Idiopathic thrombocytopenic purpura
- Thrombotic Thrombocytopenic Purpura (TTP)
- Hemolytic Uremic Syndrome (HUS)
- Disseminated Intravascular Coagulation (DIC)
- Viral infections (HIV, mumps, varicella, EBV)
- Drugs (heparin, protamine)
- Postransfusion or Posttransplantation
- Autoimmune destruction (SLE or Sarcoidosis)
- Mechanical destruction
- Artificial valves
- ECMO
- HELLP syndrome
- Excessive hemorrhage
- Hemodialysis, extracorporeal circulation
- Splenic Sequestration
- Occurs in Sickle cell disease and Cirrhosis
Drug Induced
- sulfa antibiotics, ETOH, ASA, thiazide diuretics/furosemide
Comparison by Etiology
ITP | TTP | HUS | HIT | DIC | |
---|---|---|---|---|---|
↓ PLT | Yes | Yes | Yes | Yes | Yes |
↑PT/INR | No | No | No | +/- | Yes |
MAHA | No | Yes | Yes | No | Yes |
↓ Fibrinogen | No | No | No | No | Yes |
Ok to give PLT | Yes | No | No | No | Yes |
Diagnosis
- Diagnosis of exclusion
- Must differentiate acute ITP from chronic ITP, which suggests an underlying disorder
- CBC shows normal cell lines except for the platelets (may have mild anemia)
Management
Options
- First choice in adults: Corticosteroids
- Prednisone 60-100 mg/d with taper after count reaches normal (50-75% remission rate by 3 wks)
- Methylprednisolone 30mg/kg/d IV x 3 days (for life-threatening bleeding)
- First choice in children: Intravenous Immunoglobulin G (IVIG) 1gm/kg/d x 2 days
- Anti-D (RhoGAM): patient must be Rh+ for it to work
- Causes shift towards splenic destruction of antibody-coated Rh+ RBCs
- Thereby has less functional capacity to destroy platelets
- Dosage dependent on Hb level in mg/dL[1]
- Hb>10, 250 IU/kg IV x1 over 5min
- Hb<10, 125 IU/kg IV x1 over 5min
- Platelet transfusion
- Indicated for life-threatening bleeding
- Transfuse only following first dose of methylprednisolone or IVIG
- Holding transfusion until after first dose results in greater rise in platelet count
- Estrogen for uterine bleeding: 25mg IV x1
Indications
Adults
- Plt >30K and asymptomatic: usually do not require treatment
- Plt count <30K: prednisone
- Plt <50K AND bleeding: prednisone
- Life-threatening bleeding: IVIG, methylprednisolone, platelet transfusion
Children
- Platelet count >30K: usually do not require treatment
- Platelet count <20K + significant bleeding: IVIG
- Platelet count <10K: IVIG
- Life-threatening bleeding: IVIG, methylprednisolone, platelet transfusion
Disposition
- Admit: platelet count <20K or significant mucous membrane bleeding
- Discharge: platelet count >20K AND asymptomatic OR only minor petechiae
Complications
- Rare: more common in elderly
See Also
References
- ↑ eMedicine. RhoGAM. http://reference.medscape.com/drug/rhogam-hyperrho-s-d-rho-d-immune-globulin-343143.