Rosen & Barkin's 5-Minute Emergency Medicine Consult (387 page)

• 243 Congenital hypothyroidism
  
• 244.8 Other specified acquired hypothyroidism
  
• 244.9 Unspecified acquired hypothyroidism
  

BASICS

• Idiopathic thrombocytopenic purpura (ITP) is thrombocytopenia without apparent cause or abnormalities in other celllines.
  
• Incidence is ∼2–5/100,000/yr—may be an underestimate owing to undetected, subclinical cases.
  
• Acute ITP:
  
  • 1/2 of cases involve children.
    
  • 80% of children recover within 8 wk with or without therapy.
    
  • Adult recovery is delayed and requires specific therapy to achieve remission.
    
• Chronic ITP:
  
  • Occurs mostly in adults
    
  • Young women are most susceptible in adult onset ITP
    
  • Characterized by variable response to corticosteroids and other immune suppressants
    
  • 60–70% respond to splenectomy
    
• Chronic refractory ITP:
  
  • Platelet counts may often wax and wane.
    
  • Often do not respond to therapy
    
  • No clear optimal course of treatment
    
• Genetics:
  
  • ITP appears to run in families, as do variations in response to corticosteroids for treatment.
    

• Autoantibodies produced by B cells and plasma cells cause immune-mediated destruction of circulating platelets
  
• Macrophages in spleen and liver mediate destruction of platelets via IgG autoantibodies
  
• IgM and IgA rarely have been seen
  
• Some patients do not possess autoantibodies, suggesting a role for T cell-mediated cytotoxicity.
  
• C3 and C4 complements have also been shown to play a role in patients that lack autoantibodies
  
• Poor platelet production may also play a role especially in chronic or refractory cases of ITP
  
• Eradication of
  Helicobacter pylori
  can sometimes be associated with platelet recovery (unclear mechanism).
  

DIAGNOSIS

• Bleeding is the most common complaint:
  
  • Common:
    
    • Mucous membrane: Gingiva, epistaxis, conjunctival, menorrhagia
      
  • Rare (more common in coagulopathies):
    
    • GI bleeding, hemarthrosis, hematuria, and hematomas
      
• 84% of pediatric cases are 2–3 wk following a viral illness:
  
  • Small percentage found following vaccinations
    
• Most adult cases have an insidious onset:
  
  • Up to 28% of patients are asymptomatic and diagnosed on routine CBC
    
  • <5% present with life-threatening bleeding
    

• Mucosal bleeding often apparent in symptomatic cases
  
• Commonly may follow dental procedures, extraction or trauma
  
• Petechiae (nonblanching)
  
• Nonpalpable purpura
  
• Distinguishes ITP from Henoch–Schönlein purpura (HSP)
  
• Melena, bright red blood per rectum, or hemoccult positive stools
  
• Spleen normal size in ITP:
  
  • Enlarged spleen may be found in leukemia or other platelet sequestration syndromes
    
• Neurologic deficits from intracranial hemorrhage (ICH):
  
  • ICH is the most common cause of death in ITP.
    
  • Risk of ICH in ITP increases with age:
    
    • Age <40 yr: 2%
      
    • Age >60 yr: 48%
      

• Diagnosis of exclusion—other causes of thrombocytopenia must be ruled out.
  
• CBC with differential
  
• PT and PTT if actively bleeding to exclude other forms of coagulopathy
  
• BUN and creatinine to evaluate renal function
  
• Liver function to exclude liver disease
  
• Type and screen if actively bleeding
  
• Pregnancy test if of childbearing age
  
• HIV testing should be considered
  

CBC with differential and peripheral smear:

• Thrombocytopenia
  
• Increased mean platelet volume
  
• Normal WBC and RBC morphology and size
  
• Liver function, coagulation studies, and kidney function should all be within normal limits
  

CT head without contrast to evaluate for ICH if clinically indicated by focal findings, headache, or head trauma.

Bone marrow biopsy:

• All adults >60 yr to evaluate for malignancy
  
• Atypical symptoms and cases refractory to treatment
  
• Patients considering splenectomy
  
• Children with persistent thrombocytopenia >6 mo
  
• Children unresponsive to intravenous immunoglobulin (IVIG)
  
• Antibody testing is of no clinical value
  

• Impaired bone marrow production:
  
  • Bone marrow fibrosis
    
  • Bone marrow infiltration owing to malignancy
    
  • Cytotoxic drugs used in chemotherapy
    
  • Congenital/acquired bone marrow abnormalities
    
• Splenic sequestration:
  
  • Portal hypertension
    
  • Neoplastic infiltration
    
  • Sickle cell disease
    
• Accelerated destruction of platelets:
  
  • Vasculitis
    
  • TTP/HUS
    
  • Disseminated intravascular coagulation (DIC)
    
  • HELLP syndrome
    
  • Cardiac valvular disease
    
• Drug induced:
  
  • Decreased platelet production:
    
    • Chemotherapy
      
    • Thiazide diuretics
      
    • Ethanol
      
    • Estrogen
      
  • Increased destruction of platelets:
    
    • Aspirin
      
    • Heparin
      
    • Chlorpropamide
      
    • Chloroquine
      
    • Gold salts
      
    • Sulfonamides
      
    • Insecticides
      

TREATMENT

Stabilize ABCs

• Significant oral or laryngeal bleeding may affect airway.
  
• CNS event may affect ability to control airway
  
• Establish IV access for cases of significant bleeding
  
• Control any bleeding with direct pressure
  

• ABCs
  
• Stabilize life-threatening bleeding:
  
  • ICH:
    
    • Airway control
      
    • Neurosurgery consultation: Craniotomy not typically possible until platelet counts >75 K
      
  • Hemorrhagic shock:
    
    • 2 large-bore IVs
      
    • Direct pressure for hemostasis
      
    • Resuscitation with blood transfusions and isotonic crystalloid
      
    • Medications and platelets for acute life-threatening episodes of bleeding:
      
      • IV high-dose dexamethasone or methylprednisolone
        
      • IVIG infusion
        
      • Platelet transfusions: 2–3 times the normal amount
        
  • Platelets typically infused after steroids and/or IVIG
    
  • Mucous membrane bleeding:
    
    • Topical agents
      
    • Other:
      
      • IV Aminocaproic acid may be considered
        
      • In rare cases, plasmapheresis has been proven helpful
        

• Initial treatment options for ITP are based on:
  
  • Degree of thrombocytopenia
    
  • Severity of illness
    
  • Duration of symptoms
    
  • Age
    
  • Risk factors for bleeding (hypertension, peptic ulcer disease, vigorous lifestyle)
    
  • Hematologist preference
    
• Efficacy of treatment is demonstrated in terms of platelet recovery time and not morbidity or mortality.
  
• Specific treatment options:
  
  • Observation is recommended for children without bleeding complications or profound thrombocytopenia (<20–30 K)
    
  • Profound thrombocytopenia (<20 K):
    
    • High-dose corticosteroids: 75% response
      
    • IVIG: 80% response, but costly, so reserved in time critical emergencies
      
    • Anti-D IG: 70% response (used only in Rh
      ⁺
      patients)
      
  • Splenectomy:
    
    • 2nd-line therapy if inadequate response to a course of glucocorticoid therapy
      
    • Two-thirds of adult patients respond, three-fourths of pediatric patients respond.
      
    • No specific indications for emergent splenectomy
      

• Differential diagnosis of thrombocytopenia during pregnancy:
  
  • Gestational thrombocytopenia (75%):
    
    • Usually of no clinical significance
      
    • Does not cause neonatal thrombocytopenia
      
    • Remits 1–2 wk after delivery
      
    • Platelets typically >50 K
      
• HELLP syndrome (
  h
  emolysis,
  e
  levated
  l
  iver
  e
  nzymes, and
  l
  ow
  p
  latelets)
  
• ITP (15%):
  
  • Platelets typically <50 K
    
  • Maternal platelet count does not correlate to neonatal thrombocytopenia.
    
  • Treatment with steroids or IVIG does not alter incidence of neonatal thrombocytopenia.
    
  • Degree of thrombocytopenia should not alter decision of vaginal birth vs. C-section.
    
  • Measure neonatal CBC and check brain ultrasound for ICH.
    
  • Treat neonatal thrombocytopenia with IVIG and steroids