Immune Thrombocytopenic Purpura

Aka: Immune Thrombocytopenic Purpura, Idiopathic Thrombocytopenic Purpura, ITP

advertisement

II. Definitions

  1. Immune Thrombocytopenic Purpura
    1. Premature splenic destruction of Antibody-covered Platelets, while other hematopoetic cell lines remain unaffected

III. Epidemiology

  1. Incidence: 10 cases per 100,000
  2. Children comprise 50% of ITP cases (primarily acute ITP)
    1. Most common isolated Thrombocytopenia cause in children
    2. Peak onset between ages 2 to 4 years
  3. Primary ITP
    1. Incidence: 3.3 per 100,000
    2. Prevalence: 9.5 per 100,000

IV. Pathophysiology

  1. IgG Antibody develops against Platelet membrane Antigen
  2. Acute Idiopathic Thrombocytopenic Purpura
    1. Immune complex formation and complement deposition on Platelets as a Hypersensitivity Reaction
    2. Acute onset follows Viral Exanthem or Viral Infection
    3. Occurs in otherwise healthy patients and typically children of either gender
  3. Chronic Idiopathic Thrombocytopenic Purpura
    1. Automimmune reaction with autoantibody formation, Platelet sensitization and premature removal from circulation
    2. Insidious onset in patient with immune disorder
    3. More common onset in teenage girls and women
    4. Rarely resolves spontaneously and associated with higher complication rates

V. Causes: Secondary Immune Thrombocytopenic Purpura

  1. Lymphoproliferative Disorders or Myelodysplastic Syndrome
    1. Evaluate in all patients over age 60 years with Immune Thrombocytopenic Purpura
  2. Systemic Lupus Erythematosus
  3. Antiphospholipid Syndrome
  4. Graves Disease
  5. Sarcoidosis
  6. HIV Infection
  7. Epstein-Barr Virus Infection (EBV or mononucleosus)
  8. Cytomegalovirus (CMV)
  9. Varicella-Zoster Virus
  10. Hepatitis C Virus

VI. Findings: Signs and Symptoms

  1. Preceding Viral Infection is common in children
  2. Mild symptoms (often asymptomatic)
    1. Petechiae
    2. Non-palpable Purpura
    3. Mild Splenomegaly in 5 to 10% of cases
      1. Significant Splenomegaly suggests alternative cause other than primary ITP
    4. Bleeding complications
      1. May present with mild mucosal bleeding
      2. Significant bleeding associated with severe Thrombocytopenia (Platelet Count <20k per uL)
  3. Absent signs
    1. No fever, lethargy, pallor or weight loss
    2. No bone or Joint Pain
    3. No Lymphadenopathy
    4. No Hepatomegaly

VII. Labs

  1. See Thrombocytopenia
  2. No specific test defines Immune Thrombocytopenic Purpura (diagnosis of exclusion)
    1. Exclude other Thrombocytopenia Causes first
  3. Complete Blood Count with Platelets
    1. Other than Thrombocytopenia, remainder of blood count is typically normal
    2. Platelet Count
      1. Acute, rapid drop in Platelet Count
      2. Platelet Count is typically 50k to 100k
      3. May decrease to levels at risk for life threatening bleeding (<10k/uL)

VIII. Differential Diagnosis

  1. See Thrombocytopenia
  2. See Purpura
  3. ITP is uncommon in pregnancy (<0.1%), but consider alternative diagnoses in pregnancy
    1. Gestational Thrombocytopenia
    2. Preeclampsia with HELLP Syndrome

IX. Management: General

  1. See Thrombocytopenia for hospitalization criteria
  2. Hematology Referral best within first 72 hours of diagnosis
  3. Outpatient Management Indications (most patients)
    1. Platelet Count >20k/uL AND
    2. Minimal to no bleeding AND
    3. Otherwise asymptomatic
  4. Emergent management
    1. Indications for urgent or emergent management (uncommon)
      1. Platelet Count <10,000/uL
      2. Serious Hemorrhage
      3. Urgent or emergent surgery required
    2. Platelet Transfusion
      1. Platelet Transfusion at dosing 2-3 fold greater than usual dose
      2. Platelet survival increases with IgG infusion immediately after Platelet Transfusion

X. Management: Hematology

  1. First-Line
    1. Corticosteroids
      1. Indicated for severe Thrombocytopenia
        1. Typically indicated with Platelet Count <30,000 per uL
      2. Platelets increase within a week of starting Corticosteroids
      3. Dosing
        1. Methylprednisolone 30 ml/kg/day over 20-30 min up to 1 g/day IV OR
        2. Prednisone 1-1.5 mg/kg orally daily
      4. Low dose in children with acute ITP with non-life threatening mucosal bleeding needing treatment
        1. Consider short-course of Corticosteroids (<7 days)
    2. Intravenous Immune globulin (IV IG)
      1. Dose: 1 g/kg/day for 2-3 days
    3. Rituximab (Rituxan)
  2. Refractory cases
    1. Anti-D Immune globulin
      1. May be used in Rh Positive patients
      2. May be considered as alternative to Corticosteroids
    2. Thrombopoietin receptor Agonist
    3. Splenectomy
      1. Indicated if ITP >1 year and corticosterioids and Immunoglobulin Are ineffective at maintaining adequate Platelet Counts
      2. Safe and effective (however subjects patient to lifelong Asplenia risk)
      3. May be preferred in younger patients
      4. Gadenstatter (2002) Am J Surg 184:606-10 [PubMed]

XI. Complications

  1. Intracranial Hemorrhage (ICH)
    1. Children: 0.5%
    2. Adults: 1.5%
  2. Severe non-ICH Bleeding
    1. Children: 3-20%
    2. Adults: 10%

XII. Prognosis

  1. Children: Acute Idiopathic Thrombocytopenic Purpura
    1. Less severe in children
    2. Recovery within 6 to 12 months for 80-90% of children
    3. Most cases resolve within weeks
  2. Adults
    1. More chronic, insidious course than for adults
    2. High complication rates

XIII. References

  1. Merrill and Gillen (2016) Crit Dec Emerg Med 30(3): 3-8
  2. Blanchette (2000) Semin Hematol 37(3):299-314 [PubMed]
  3. Bolton-Maggs (2000) Arch Dis Child 83(3):220-2 [PubMed]
  4. Gauer (2022) Am Fam Physician 106(3): 288-98 [PubMed]
  5. Gauer (2012) Am Fam Physician 85(6): 612-22 [PubMed]
  6. George (1996) Blood 88:3-40 [PubMed]
  7. Jones (2024) Am Fam Physician 110(1): 58-64 [PubMed]
  8. Neunert (2019) Blood Adv 3(23): 3829-66 [PubMed]
  9. Souid (1995) Clin Pediatr 34:487-94 [PubMed]

Images: Related links to external sites (from Bing)

These images are a random sampling from a Bing search on the term "Immune Thrombocytopenic Purpura." Click on the image (or right click) to open the source website in a new browser window. Search Bing for all related images

Related Topics in Platelet Disorders

advertisement