Immune thrombocytopenic purpura (peds)

This page is for pediatric patients. For adult patients, see: Immune thrombocytopenic purpura or ITP in Pregnancy for pregnancy related.

Background

• Also known as immune thrombocytopenia (ITP), an acquired immune-mediated thrombocytopenia
  • Hallmark is isolated thrombocytopenia
• Pathophysiology: Autoantibodies to platelet membrane antigens (ex. GpIIb//IIIa) lead to splenic clearance of platelets and limit production
• Can be primary or secondary (medications, systemic illness, infection, autoimmune disorder)
• Primary peak is in early childhood (2-5 years) with a smaller peak in adolescence
• ITP is a diagnosis of exclusion; first consider all serious causes of petechiae/purpura including meningococcemia, DIC, HUS, TTP, Leukemia, etc

Acute vs Chronic ITP

Charateristic	Acute ITP	Chronic ITP
Common age group	Younger children	Adults
Sex	Affects men/women equally	Usually women
Duration	Resolves in 1-2 months	Lasts > 3 months
Cause	Typically follows viral illness	More likely to have an underlying disease or autoimmune disorder (e.g. SLE)
Prognosis		Rarely remits spontaneously or with treatment

Clinical Features

Petechiae in a patient with ITP.

Petechiae on the tongue in a patient with ITP.

Petechiae on the lower leg in a patient with ITP.

Unprovoked gingival bleeding as a presenting symptom in ITP.

• Usually well-appearing without constitutional symptoms
• Isolated petechial rash or bruising is often the first clinical feature
  • Most have "dry" bleeding consisting of petechiae, purpura, and ecchymoses
  • May have "wet" bleeding such as oral/nasal bleeding
  • Severe or intracranial bleeding is rare, but have a high index of suspicion in the appropriate context
• May have a preceding systemic illness
  • >70% of pediatric cases occur after viral infections
• May have exposure to recent vaccinations (particularly MMR) or drugs known to cause thrombocytopenia: Heparin, Quinidine, Phenytoin, Sulfa drugs, Valproate and Vancomycin

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

Evaluation

Workup

• CBC
• Peripheral blood smear to assess for atypical cell lines, hemolytic anemia, and platelet quantity/quality
• Coags if heavy bleeding
  • Results are typically normal in ITP
• Type and Screen
  • Blood typing can determine Rh status; only Rh+ patients should be treated with RhoGAM
  • RhoGAM coats RBCs to later bind Fc gamma receptor in the reticuloendothelial system (spleen), which interferes with the removal of antibody-coated platelets 
• There is no role for antiplatelet antibody testing due to lack of sensitivity/specificiy

Diagnosis

• Platelet count of < 100,000/microL is usually the only finding on a CBC
  • Consider alternate diagnoses, including leukemia/lymphoma, when other cell lines are abnormal
  • Usually < 30,000/microL.
• Remainder of the CBC is typically normal, unless there is significant bleeding (Hgb could be low)
• Peripheral blood smear shows fewer than normal platelets and increased mean platelet volume (due to younger, larger platelets/megakaryocytes)
  • Leukocytes and RBCs should be morphologically normal

Management

• Consult pediatric hematologist
• Avoid activity that could increase risk of trauma, especially head trauma
• Avoid NSAIDs and anticoagulants
• Therapy is based on degree of bleeding; first-line therapy includes different combinations of corticosteroids and IVIG or RhoGAM (use only for Rh+ patients)
  • Most children (85%) have a self-resolving course and do not require treatment.
  • Low-risk bleeding: Watchful waiting
  • Moderate to high-risk bleeding: IVIG or RhoGAM if significant bleeding or if preparing for procedure
  • Severe bleeding, non-life threatening: Platelet transfusion if needed. Methylprednisolone, IVIG and/or RhoGAM for up to 4 days. Possibly Romiplostim (thrombopoietin receptor agonist) or TXA.
  • Life threatening bleeding: Platelet transfusion, methylprednisolone x 3-4 days, IVIG x 1-3 days.

Disposition

• Low-risk patients may be discharged with short-term follow up
• Moderate to high-risk patients or those with severe bleeding should be admitted

See Also

• ITP (adult)
• ITP in Pregnancy
• TTP

References

• Duncan, Ellen. Immune Thrombocytopenia. PEM GUIDES. 7th edition. NYU Langone Health; 2020: 459-462.