Thrombocytopenia

Aka: Thrombocytopenia, Low Platelets, Low Platelet Count

1. Definition
   1. Decreased Platelet Count
2. See Also
   1. Thrombocytopenia Causes
   2. Platelet Dysfunction
   3. Purpura
3. History
   1. Family History of Thrombocytopenia
      1. Consider congenital Thrombocytopenia Causes
   2. Comorbid conditions
      1. Liver disease
      2. Heart Valve Replacement
   3. Pregnancy
      1. Gestational Thrombocytopenia
      2. Preeclampsia with HELLP Syndrome
   4. Social history
      1. Alcohol Abuse
   5. Recent international travel (especially tropical)
      1. Dengue fever
      2. Malaria
      3. Rickettsial Disease
   6. Medications
      1. Drug-Induced Thrombocytopenia
      2. Heparin-Induced Thrombocytopenia
      3. Chemotherapy
      4. Radiation Therapy
      5. Immunizations (MMR, Varicella, H1N1 Influenza Vaccine)
      6. Transfusion
         1. Transfusion reaction
         2. Infection (Hepatitis C or HIV Infection)
4. Symptoms: Clues to Thrombocytopenia Causes
   1. Abdominal Pain
      1. HELLP Syndrome
      2. Hemolytic Uremic Syndrome
      3. Platelet Sequestration (Splenomegaly)
   2. Fever
      1. Viral Infections (e.g. CMV, EBV, VZV, HIV, HCV, Parvovirus B19)
      2. Dengue fever
      3. Malaria
      4. Rickettsial Disease
   3. Weight loss or Night Sweats
      1. HIV Infection
      2. Leukemia
      3. Myelodysplastic Syndrome
5. Signs: Clues to Thrombocytopenia Causes
   1. Rash
      1. Viral Exanthems (VZV, Parvovirus B19)
      2. Rickettsial infections
      3. Systemic Lupus Erythematosus
   2. Generalized Lymphadenopathy
      1. Viral Infections (e.g. CMV, EBV, HIV)
      2. Systemic Lupus Erythematosus
      3. Leukemia, Lymphoma and other hematiologic malignancies
   3. Hepatomegaly
      1. Chronic Liver Disease
      2. Leukemia
      3. Viral Infections (CMV, EBV, HCV)
   4. Splenomegaly
      1. Viral Infections (CMV, EBV)
   5. Neurologic findings
      1. Thrombotic Thrombocytopenic Purpura
6. Causes
   1. See Thrombocytopenia Causes
7. Labs: Platelet Count Interpretation
   1. Platelet Count 70,000 to 150,000 per uL
      1. Mild Thrombocytopenia
   2. Platelet Count 50,000 to 70,000 per uL
      1. Asymptomatic Moderate Thrombocytopenia
   3. Platelet Count 30,000 to 50,000 per uL
      1. Symptomatic Moderate Thrombocytopenia with excessive bleeding on traumatic injury
   4. Platelet Count 30,000 to 50,000 per uL
      1. Symptomatic Moderate Thrombocytopenia with excessive bleeding on traumatic injury
   5. Platelet Count 10,000 to 30,000 per uL
      1. Severe Thrombocytopenia with excessive bleeding with minimal Skin Trauma
   6. Platelet Count 5,000 to 10,000 per uL
      1. Severe Thrombocytopenia with risk of spontaneous bleeding, bruising or Petechiae
      2. Spontaneous bleeding requiring intervention (e.g. Nasal Packing for Epistaxis) required in 42% of patients
   7. Platelet Count below 5,000 per uL
      1. Emergent Thrombocytopenia with high risk of major spontaneous bleeding (e.g. gastrointestinal tract, genitourinary tract)
8. Labs: Initial Evaluation of Thrombocytopenia
   1. Complete Blood Count (CBC)
   2. Peripheral Blood Smear
      1. See Platelet Morphology
      2. See Peripheral Blood Smear
   3. Platelet Count
      1. Consider repeat Platelet Count in non-EDTA Anticoagulant (rules-out Pseudothrombocytopenia)
      2. Repeat Platelet Count timing (adjust based on chronicity, stability and bleeding complications)
         1. Repeat immediately for developing bleeding complications
         2. Repeat in days to 1 week if Platelet Count <50,000 per uL
         3. Repeat in 2 weeks if Platelet Count <100,000 per uL
         4. Repeat in 4 weeks if Platelet Count <150,000 per uL
9. Management: Hematology Referral Indications for Thrombocytopenia
   1. Leukopenia or Leukocytosis
   2. Anemia
   3. Peripheral Blood Smear abnormalities
   4. Symptomatic Thrombocytopenia with Bleeding Diathesis, Petechiae, Purpura or Ecchymosis
   5. Platelet Count <50,000 per uL (or persistently below 100,000 per uL on repeat testing)
10. Management: Activity and Procedure Limitations
    1. Platelet Count >50,000 per uL
       1. No limitations to activity or procedures
       2. Use caution in collision sports with Thrombocytopenia
       3. Most surgical procedures can be perfromed safely at this Platelet Count
       4. Epidural Anesthesia is safe at 50,000 per uL, but >100,000 per uL is preferred
    2. Platelet Count >20,000 per uL
       1. Bone Marrow Biopsy, bronchoscopy and endoscopy can be performed
    3. Platelet Count <10,000 per uL
       1. Avoid collision sports and other activities with risk of traumatic injury
11. References
    1. Gauer (2012) Am Fam Physician 85(6): 612-22
    2. George (2000) Lancet 355(9214):1531-9
    3. Goldstein (1996) Am Fam Physician 53(3):915-20
    4. Rizvi (1999) Curr Opin Hematol 6(5):349-53