Wednesday, 25 May 2022
Immune Thrombocytopenic Purpura
Topic Review
De nition:
Immune thrombocytopenia (ITP) of childhood is characterized by isolated
thrombocytopenia (platelet count <100,000/microL with normal white blood cell count,
hemoglobin, and blood smear).
The cause of ITP remains unknown in most cases, but it can be triggered by a viral or
environmental trigger or it may be secondary to an underlying immunologic defect.
ITP was previously known as idiopathic thrombocytopenic purpura or immune
thrombocytopenic purpura. The current term Immune ThrombocytoPenia preserves the
widely-recognized acronym "ITP," while acknowledging the immune-mediated mechanism
of the disorder and that patients may have little or no signs of purpura or bleeding
Classi cation:
Primary immune thrombocytopenia: an autoimmune disorder characterized by isolated
thrombocytopenia (< 100,000/mm3) in the absence of other causes or disorders that may
be associated with the thrombocytopenia.
Primary ITP is categorized into three phases, depending on the length of the
disease course:
Newly diagnosed ITP: all cases within the rst 3 months of diagnosis
Persistent ITP: ITP lasting 3–12 months
Chronic ITP: ITP lasting > 12 months
Secondary immune thrombocytopenia: an autoimmune hematologic disorder causing
isolated thrombocytopenia that is secondary to an identi able trigger, including drug-
induced or associated with systemic illness, such as systemic lupus erythematosus (SLE),
infection (eg, HIV), immune de ciency (eg, common variable immunode ciency [CVID] or
autoimmune lymphoproliferative syndrome [ALPS]), and other causes.
Epidemiology in Children:
Highest prevalence in children < 5 years of age
Typically self-limiting after a viral infection; 80% of cases resolve within 12
months
Pathophysiology:
Antiplatelet antibodies (mostly IgG directed against, e.g., GpIIb/IIIa, GpIb/IX) bind to
surface proteins on platelets → sequestration by spleen and liver → ↓ platelet count
→ bone marrow megakaryocytes and platelet production increase in response (in
most cases)
Clinical features:
There should be suspicion for ITP in a child with thrombocytopenia and petechiae
following a viral illness!
Clinical features can correlate with platelet count
1
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Immune Thrombocytopenic Purpura
Topic Review
De nition:
Immune thrombocytopenia (ITP) of childhood is characterized by isolated
thrombocytopenia (platelet count <100,000/microL with normal white blood cell count,
hemoglobin, and blood smear).
The cause of ITP remains unknown in most cases, but it can be triggered by a viral or
environmental trigger or it may be secondary to an underlying immunologic defect.
ITP was previously known as idiopathic thrombocytopenic purpura or immune
thrombocytopenic purpura. The current term Immune ThrombocytoPenia preserves the
widely-recognized acronym "ITP," while acknowledging the immune-mediated mechanism
of the disorder and that patients may have little or no signs of purpura or bleeding
Classi cation:
Primary immune thrombocytopenia: an autoimmune disorder characterized by isolated
thrombocytopenia (< 100,000/mm3) in the absence of other causes or disorders that may
be associated with the thrombocytopenia.
Primary ITP is categorized into three phases, depending on the length of the
disease course:
Newly diagnosed ITP: all cases within the rst 3 months of diagnosis
Persistent ITP: ITP lasting 3–12 months
Chronic ITP: ITP lasting > 12 months
Secondary immune thrombocytopenia: an autoimmune hematologic disorder causing
isolated thrombocytopenia that is secondary to an identi able trigger, including drug-
induced or associated with systemic illness, such as systemic lupus erythematosus (SLE),
infection (eg, HIV), immune de ciency (eg, common variable immunode ciency [CVID] or
autoimmune lymphoproliferative syndrome [ALPS]), and other causes.
Epidemiology in Children:
Highest prevalence in children < 5 years of age
Typically self-limiting after a viral infection; 80% of cases resolve within 12
months
Pathophysiology:
Antiplatelet antibodies (mostly IgG directed against, e.g., GpIIb/IIIa, GpIb/IX) bind to
surface proteins on platelets → sequestration by spleen and liver → ↓ platelet count
→ bone marrow megakaryocytes and platelet production increase in response (in
most cases)
Clinical features:
There should be suspicion for ITP in a child with thrombocytopenia and petechiae
following a viral illness!
Clinical features can correlate with platelet count
1
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