Updated: 10/26/2018

Immune Thrombocytopenia (ITP)

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Snapshot
  • A 38-year-old man presents to his primary care physician's office for episodes of epistaxis and gingival bleeding. He reports his symptoms began one day prior to presentation and has never occurred before. He denies starting any new medications. Social history is notable for current intravenous drug use. On physical exam, there is blood in the nares and mild bleeding of the gums. There are petechiae distal to where the blood pressure cuff was placed. Abdominal exam is unremarkable. A complete blood count is significant for a platelet count of 28,000/μL and peripheral blood smear demonstrates enlarged platelets. 
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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Questions (2)
Lab Values
Blood, Plasma, Serum Reference Range
ALT 8-20 U/L
Amylase, serum 25-125 U/L
AST 8-20 U/L
Bilirubin, serum (adult) Total // Direct 0.1-1.0 mg/dL // 0.0-0.3 mg/dL
Calcium, serum (Ca2+) 8.4-10.2 mg/dL
Cholesterol, serum Rec: < 200 mg/dL
Cortisol, serum 0800 h: 5-23 μg/dL //1600 h:
3-15 μg/dL
2000 h: ≤ 50% of 0800 h
Creatine kinase, serum Male: 25-90 U/L
Female: 10-70 U/L
Creatinine, serum 0.6-1.2 mg/dL
Electrolytes, serum  
Sodium (Na+) 136-145 mEq/L
Chloride (Cl-) 95-105 mEq/L
Potassium (K+) 3.5-5.0 mEq/L
Bicarbonate (HCO3-) 22-28 mEq/L
Magnesium (Mg2+) 1.5-2.0 mEq/L
Estriol, total, serum (in pregnancy)  
24-28 wks // 32-36 wks 30-170 ng/mL // 60-280 ng/mL
28-32 wk // 36-40 wks 40-220 ng/mL // 80-350 ng/mL
Ferritin, serum Male: 15-200 ng/mL
Female: 12-150 ng/mL
Follicle-stimulating hormone, serum/plasma Male: 4-25 mIU/mL
Female: premenopause: 4-30 mIU/mL
midcycle peak: 10-90 mIU/mL
postmenopause: 40-250
pH 7.35-7.45
PCO2 33-45 mmHg
PO2 75-105 mmHg
Glucose, serum Fasting: 70-110 mg/dL
2-h postprandial:<120 mg/dL
Growth hormone - arginine stimulation Fasting: <5 ng/mL
Provocative stimuli: > 7ng/mL
Immunoglobulins, serum  
IgA 76-390 mg/dL
IgE 0-380 IU/mL
IgG 650-1500 mg/dL
IgM 40-345 mg/dL
Iron 50-170 μg/dL
Lactate dehydrogenase, serum 45-90 U/L
Luteinizing hormone, serum/plasma Male: 6-23 mIU/mL
Female: follicular phase: 5-30 mIU/mL
midcycle: 75-150 mIU/mL
postmenopause 30-200 mIU/mL
Osmolality, serum 275-295 mOsmol/kd H2O
Parathyroid hormone, serume, N-terminal 230-630 pg/mL
Phosphatase (alkaline), serum (p-NPP at 30° C) 20-70 U/L
Phosphorus (inorganic), serum 3.0-4.5 mg/dL
Prolactin, serum (hPRL) < 20 ng/mL
Proteins, serum  
Total (recumbent) 6.0-7.8 g/dL
Albumin 3.5-5.5 g/dL
Globulin 2.3-3.5 g/dL
Thyroid-stimulating hormone, serum or plasma .5-5.0 μU/mL
Thyroidal iodine (123I) uptake 8%-30% of administered dose/24h
Thyroxine (T4), serum 5-12 μg/dL
Triglycerides, serum 35-160 mg/dL
Triiodothyronine (T3), serum (RIA) 115-190 ng/dL
Triiodothyronine (T3) resin uptake 25%-35%
Urea nitrogen, serum 7-18 mg/dL
Uric acid, serum 3.0-8.2 mg/dL
Hematologic Reference Range
Bleeding time 2-7 minutes
Erythrocyte count Male: 4.3-5.9 million/mm3
Female: 3.5-5.5 million mm3
Erythrocyte sedimentation rate (Westergren) Male: 0-15 mm/h
Female: 0-20 mm/h
Hematocrit Male: 41%-53%
Female: 36%-46%
Hemoglobin A1c ≤ 6 %
Hemoglobin, blood Male: 13.5-17.5 g/dL
Female: 12.0-16.0 g/dL
Hemoglobin, plasma 1-4 mg/dL
Leukocyte count and differential  
Leukocyte count 4,500-11,000/mm3
Segmented neutrophils 54%-62%
Bands 3%-5%
Eosinophils 1%-3%
Basophils 0%-0.75%
Lymphocytes 25%-33%
Monocytes 3%-7%
Mean corpuscular hemoglobin 25.4-34.6 pg/cell
Mean corpuscular hemoglobin concentration 31%-36% Hb/cell
Mean corpuscular volume 80-100 μm3
Partial thromboplastin time (activated) 25-40 seconds
Platelet count 150,000-400,000/mm3
Prothrombin time 11-15 seconds
Reticulocyte count 0.5%-1.5% of red cells
Thrombin time < 2 seconds deviation from control
Volume  
Plasma Male: 25-43 mL/kg
Female: 28-45 mL/kg
Red cell Male: 20-36 mL/kg
Female: 19-31 mL/kg
Cerebrospinal Fluid Reference Range
Cell count 0-5/mm3
Chloride 118-132 mEq/L
Gamma globulin 3%-12% total proteins
Glucose 40-70 mg/dL
Pressure 70-180 mm H2O
Proteins, total < 40 mg/dL
Sweat Reference Range
Chloride 0-35 mmol/L
Urine  
Calcium 100-300 mg/24 h
Chloride Varies with intake
Creatinine clearance Male: 97-137 mL/min
Female: 88-128 mL/min
Estriol, total (in pregnancy)  
30 wks 6-18 mg/24 h
35 wks 9-28 mg/24 h
40 wks 13-42 mg/24 h
17-Hydroxycorticosteroids Male: 3.0-10.0 mg/24 h
Female: 2.0-8.0 mg/24 h
17-Ketosteroids, total Male: 8-20 mg/24 h
Female: 6-15 mg/24 h
Osmolality 50-1400 mOsmol/kg H2O
Oxalate 8-40 μg/mL
Potassium Varies with diet
Proteins, total < 150 mg/24 h
Sodium Varies with diet
Uric acid Varies with diet
Body Mass Index (BMI) Adult: 19-25 kg/m2
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