questions 4

Immune Thrombocytopenia (ITP)

Topic updated on 11/06/17 10:17am

Snapshot
  • A 42-year-old man presents to his primary care physician's office for easy bruising and gingival bleeding. He reports his symptoms began one day prior to presentation and has never occurred before. Medical history is significant for a recently diagnosed hepatitis C infection. On physical exam, there is mild bleeding of the gums. There are petechiae throughout the chest, arms, and legs. There is no evidence of splenomegaly on abdominal exam. A complete blood count is significant for a platelet count of 24,000/μL and peripheral blood smear demonstrates enlarged platelets. He is started on corticosteroids.
Introduction
  • Clinical definition
    • acquired immune-mediated destruction of otherwise normal platelets
  • Classification
    • primary immune thrombocytopenia (ITP)
      • immune-mediated thrombocytopenia without an underlying condition
    • secondary ITP
      • immune-mediated thrombocytopenia with an underlying condition (e.g., HIV infection)
  • Epidemiology
    • demographics
      • 1-7 years of age commonly in children
  • Etiology
    • primary ITP
      • unknown
    • secondary ITP
      • autoimmune disorders
        • systemic lupus erythematosus
        • antiphospholipid syndrome
      • infection 
        • HIV
        • hepatitis C virus
      • malignancy
        • chronic lymphocytic leukemia
      • vaccinations
  • Pathogenesis
    • IgG antibodies directed against platelet membrane glycoproteins such as GPIIb/IIIa
      • a type II hypersensitivity reaction
Presentation
  • Symptoms
    • asymptomatic
    • bleeding symptoms
      • gingival bleeding
      • epistaxis
  • Physical exam
    • petechiae
    • purpura
    • ecchymosis
    • atypical to have a palpable spleen
Studies
  • Making the diagnosis
    • primary ITP
      • isolated thrombocytopenia (e.g., < 100,000/μL) without a known cause
    • secondary ITP
      • isolated thrombocytopenia (e.g., < 100,000/μL) with an underlying condition (e.g., positive for HIV infection)
Differential
  • Hypersplenism
    • distinguishing factor
      • splenomegaly
  • Liver disease
    • distinguishing factor
      • elevated transaminases and hepatosplenomegaly
      • coagulation abnormalities may be present
  • Microangiopathic hemolytic process (e.g., thrombotic thrombocytopenic purpura)
    • distinguishing factor
      • schistocytes are appreciated on peripheral blood smear
Treatment
  • Conservative
    • observation
      • indication
        • in patients with a platelet count > 30,000/μL and no bleeding
  • Medical
    • corticosteroids  
      • indication
        • initial treatment for patients with a platelet count < 30,000/μL
    • intravenous immunoglobulins (IVIG) 
      • indication
        • for patients with a platelet count < 30,000/μL who have contraindications to corticosteroids, are refractory to corticosteroid treatment, or are bleeding or have a high risk of bleeding that will need a rapid increase in platelet count
  • Operative
    • splenectomy
      • indication
        • second-line treatment for patients with refractory ITP
Complications
  • Fatal hemorrhage


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Qbank (1 Questions)

TAG
(M3.HE.52) A 66-year-old man presents to his primary care physician endorsing easy bleeding. He reports that roughly 5 days ago, he began noticing excessive bleeding while brushing his teeth, and yesterday he had one episode of hematuria. He is otherwise healthy with a medical history including hypertension treated with amlodipine and depression for which he takes fluoxetine; he is up to date on all recommended screening. On examination, he is well-appearing; his lower extremities have numerous small non-blanching erythematous macules; no active bleeding is seen in his oropharynx. His primary care physician orders a complete blood cell count that reveals a white blood cell count of 7000/uL, hemoglobin of 12 g/dL, and platelet count of 34,000/uL. Peripheral blood smear is shown in Figure A. Which of the following is the most appropriate next step in management? Topic Review Topic
FIGURES: A          

1. Close clinical observation and follow-up
2. Prednisone
3. Rituximab
4. Intravenous immunoglobulin (IVIG)
5. Platelet transfusion

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