What is the initial workup and treatment for a patient with thrombocytopenia (low platelet count)?

Initial Workup and Treatment for Thrombocytopenia

The initial workup for thrombocytopenia should include confirmation of true thrombocytopenia, determination of severity, evaluation of potential causes, and treatment based on severity and underlying etiology. 1, 2

Confirmation and Classification of Thrombocytopenia

1. Confirm true thrombocytopenia:

   • Collect blood in a tube containing heparin or sodium citrate to exclude pseudothrombocytopenia 2
   • Review previous platelet counts to distinguish acute from chronic thrombocytopenia 2

2. Classify severity 1:

   • Mild: 50-150 × 10⁹/L
   • Moderate: 20-50 × 10⁹/L
   • Severe: <20 × 10⁹/L
   • Very severe: <10 × 10⁹/L

Diagnostic Evaluation

1. Laboratory workup:

   • Complete blood count (CBC) with peripheral blood smear
   • Coagulation studies (PT, PTT, fibrinogen)
   • Liver function tests
   • Renal function tests
   • HIV and hepatitis C testing 3

2. Medication review:

   • Evaluate for potential drug-induced thrombocytopenia
   • Common culprits: heparin, glycoprotein IIb/IIIa inhibitors, vancomycin, linezolid, beta-lactam antibiotics, quinine, antiepileptic drugs 4

3. Clinical assessment for common causes:

   • Isolated thrombocytopenia: likely immune thrombocytopenia (ITP) or drug-induced 2
   • Thrombocytopenia with systemic illness: consider sepsis, DIC, TTP/HUS, HELLP syndrome 2
   • Recent heparin exposure: evaluate for heparin-induced thrombocytopenia (HIT) 4, 5
   • Liver disease: assess for hypersplenism and decreased thrombopoietin production 2

Treatment Approach

1. Emergency management for severe thrombocytopenia or active bleeding:

   • Platelet transfusion for:
     • Active hemorrhage
     • Platelet count <10 × 10⁹/L
     • Before invasive procedures (with count thresholds specific to procedure type) 1, 2

2. Procedure-specific platelet thresholds 1:

   • Central venous catheter insertion: >20 × 10⁹/L
   • Lumbar puncture: >40-50 × 10⁹/L
   • Epidural anesthesia: >80 × 10⁹/L
   • Major surgery: >50 × 10⁹/L
   • Neurosurgery: >100 × 10⁹/L

3. Cause-specific treatment:

   • Drug-induced thrombocytopenia: Discontinue the offending medication 4
   • Immune thrombocytopenia (ITP):
     • For insufficient response to corticosteroids, immunoglobulins, or splenectomy:
     • Consider romiplostim (Nplate) starting at 1 mcg/kg weekly subcutaneously
     • Adjust dose by increments of 1 mcg/kg to achieve platelet count ≥50 × 10⁹/L
     • Maximum weekly dose: 10 mcg/kg 6
   • Heparin-induced thrombocytopenia (HIT):
     • Immediately discontinue all heparin products
     • Initiate non-heparin anticoagulant (argatroban, bivalirudin, danaparoid, fondaparinux, or DOAC) 1, 5

Monitoring and Follow-up

• For patients on romiplostim: Obtain CBC with platelet count weekly during dose adjustment phase, then monthly after establishing stable dose 6
• For all patients: Continue monitoring until platelet count normalizes 1
• After discontinuing romiplostim: Monitor CBC with platelet count weekly for at least 2 weeks 6

Activity Restrictions and Patient Education

• Patients with platelet counts <50 × 10⁹/L should avoid activities with high risk of trauma 1, 2
• Limit alcohol intake (≤1 drink/week) and avoid binge drinking 1
• Avoid medications that affect platelet function (aspirin, NSAIDs) 1
• Report any new bleeding symptoms immediately 1

Common Pitfalls to Avoid

• Failure to distinguish between primary and secondary thrombocytopenia 1
• Missing underlying conditions causing persistent thrombocytopenia 1
• Unnecessary withholding of appropriate thromboprophylaxis 1
• Overtreatment of secondary thrombocytosis with antiplatelet agents 1
• Failure to recognize potentially life-threatening causes requiring emergency intervention (HIT, TTP/HUS, HELLP syndrome) 2, 4