Immune (idiopathic)
Thrombocytopenic
Purpura
Epidemiology
The most common cause of acute onset of thrombocytopenia (usually <20K) in
an otherwise healthy child
A recent history of viral illness is described in 50-60% of cases of childhood ITP
Typically 1-4 weeks after exposure
Peak age 2-6y
Slightly increased risk of developing ITP within 6 weeks of MMR vaccine (2.6
per 100,000 doses)
Pathogenisis
Autoantibody directed against
platelet surface (glycoprotein
complex IIb/IIIa) After binding,
circulating antibody-coated
platelets are destroyed by splenic
macrophages
In chronic ITP, T cell mediated
cytotoxicity may cause platelet
destruction
Diagnosis
ITP is a clinical diagnosis and diagnosis of exclusion
PLT <100K
Otherwise normal CBC including WBC, Hgb, reticulocyte counts
No abnormalities on peripheral smear (no evidence of hemolysis or blasts)
Negative DAT
No findings on history or PE to suggest alternative dx (systemic symptoms, palpable lymph nodes, splenomegaly)
Hemoglobin, WBC, and differential should all be normal
Consider bone marrow aspiration if abnormal
A DAT (Coombs) should be performed if unexplained anemia to rule out Evans syndrome (autoimmune
hemolytic anemia w/ thrombocytopenia) before giving anti-D
Diagnosis:2 criteria
1.Isolated thrombocytopenia,with otherwise normal blood counts and peripheral smear.
2.No clinically apparent associated conditions that may cause thrombocytopenia
Exclude concurrent inf/autoimmune disorders/malignancy/drugs/genetic bleeding disorders/ marrow failure
Differential Diagnosis
Viral infection(IMN,Hepatitis,HIV- 1)
Drug exposure(Heparin, Quinidine, Sulfonamide)
Autoimmune Disorders(SLE)
Leukemia (ALL)
Acquired marrow failure syndrome (aplastic anemia)
Inherited thrombocytopenic disorders(thrombocytopenia-absent radius
syndrome, Wiskott-Aldrich syndrome,mutation of MYH 9 gene)
Clinical Presentation
Sudden appearance of bruising and/or bleeding in an otherwise healthy child
Mild if bruising and petechiae
Moderate if presence of mucosal lesions
Severe if significant bleeding episodes (i.e. menorrhagia, epistaxis, melena
In one large cohort study, mucosal bleeding was more common with PLT count <10K compared with >15K
(51% vs 19%)
Approximately 80% will have PLT <20K at presentation, and 45% will have PLT <10K
History:
No systemic symptoms
Presence of systemic symptoms like fever ,anorexia, joint pain, bone pain or weight loss usually points to
other diagnosis
Drug induced (heparin, quinidine, sulfonamides) thrombocytopenia is uncommon in kids
Disease course: 70% of children have the acute form of ITP, which is defined by recovery (platelet count
>150,000/ micro L) in 6 months of presentation with or without treatment. Treatment do not affect the
long term outcome,but minimize the risk of significant bleeding
Treatment
Ideal management still unclear: observation alone vs observation with
pharmacologic intervention
Initial approach includes no therapy other than education and counseling with
minimal, mild, or moderate symptoms
Restrict contact sports/physical activity
Avoid medications with antiplatelet or anticoagulant activities
Platelet transfusion is usually contraindicated unless there is life-threatening
bleeding due to binding of antiplatelet antibodies to transfused platelets
Presence of severe life threatening bleeding, risk of significant bleeding
(planned procedures/count <10K, and cutaneous bleeding), comorbid
conditions (hemophilia) requires intervention
IV IG:
Mechanism of action is multi-factorial,inhibition of antibody adsorption to
platelets,prevention of RES uptake of auto ab coated platelets, interaction of
auto abs with idiotype abs in IV IG.
Works better than steroids but higher cost
Dose:
400mg /kg/day x 5 days
OR
Single dose of 1g/kg
IVIG induces rapid rise in platelet count in 95% of patients within 48hrs
IVIG appears to induce a response by downregulating Fc-mediated phagocytosis of
antibody-coated platelets
IV IG – 500 mg /kg/day x 2 days ,and may be repeated if the symptoms recur
Corticosteroids:
DO NOT GIVE STEROIDS UNTILL OTHER DIAGNOSIS ARE EXCLUDED,AS THE
STEROIDS CAN MASK EARLY LEUKEMIA.
Reduce Ab production,RES phagocytosis of antibody coated platelets,improve
vascular integrity, improve platelet production
Prednisone 1-2 mg/kg/day(max 60 /day) in 3 divided doses x 2-4 wks, followed
by a taper of 4mg / kg/day ,divided into 3 doses for 4 days
OR
Methylprednisolone( 30-50 mg /kg/day) for 3-7 days
Some cases may need repeat courses
CORTICOSTEROIDS-short course/pulse course
Anti-D for Rh positive patients
Anti-Rho(D) immune globulin: has been shown to be effective
Platelet transfusion: used in case of life threatening bleeding(ICH)
The therapy is targeted to increase count to >20,000.In risk of life
threatening bleeding , IV IG could be repeated or combined with steroids
Monitoring: the patients getting pharmacologic intervention the usual hospital
stay is 2 days.In the ambulatory setting ,platelet count monitored 1-2 times
/wk ,interval can increase as the platelet increase .monitoring is necessary
until the count return to >150,000/microL(50% in 1 mont,70% in 3 months)
Chronic ITP
Approximately 10-20% of children who initially present with ITP will become
chronic defined as PLT <100K for >12 months
Risk factors include older age, higher presenting platelet count at diagnosis,
insidious onset of symptoms, and lack of preceding infection or vaccination
Chronic ITP: persistent thrombocytopenia(<150,000/microL) for > 6 months
20-30% will have chronic ITP
1/3 rd of the cases will have spontaneous remission in months to years
In chronic ITP the platelet count ranges between 20,000-75,000/microL.usually
do not require any treatment
Management: decrease the risk for bleeding.
Role of Splenectomy
Older child >4yoa with severe ITP lasting >1 year (chronic ITP)
Symptoms not easily controlled with therapy
Life-threatening hemorrhage complicating acute ITP
Platelet count cannot be corrected rapidly with transfusion of platelets and
administration of IVIG and corticosteroids
SPLENECTOMY- may be needed in patients needing repeated /continuous
pharmacologic intervention even 12 months after diagnosis
Prognosis
Father asked question is it going to happen again
Severe bleeding is rare (<3% of cases)
ICH occurs in <1% of patients
70-80% will have spontaneous resolution in 6 months
Approximately 20% who present with acute ITP will go on to have chronic ITP
This increases to 50% in adolescents
Take Away points
References
UpToDate
D'Orazio JA, Neely J, Farhoudi N. ITP in children: pathophysiology and current
treatment approaches. J Pediatr Hematol Oncol 2013; 35:1.
Provan D, Stasi R, Newland AC, et al. International consensus report on the
investigation and management of primary immune thrombocytopenia. Blood
2010; 115:168.
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