Initial Workup and Treatment for Thrombocytopenia
The initial workup for thrombocytopenia should first exclude pseudothrombocytopenia by collecting blood in a tube containing heparin or sodium citrate and repeating the platelet count, followed by determining if the condition is acute or chronic by reviewing previous platelet counts. 1
Definition and Clinical Presentation
Thrombocytopenia is defined as a platelet count less than 150 × 10³/μL. The clinical presentation varies based on platelet count severity:
- >50 × 10³/μL: Generally asymptomatic 1
- 20-50 × 10³/μL: Mild skin manifestations (petechiae, purpura, ecchymosis) 1
- <10 × 10³/μL: High risk of serious bleeding 1
Initial Diagnostic Workup
Confirm true thrombocytopenia:
- Rule out pseudothrombocytopenia by collecting blood in a tube with heparin or sodium citrate
- Repeat platelet count to confirm finding
Determine chronicity:
- Review previous platelet counts to distinguish acute from chronic thrombocytopenia
- Acute thrombocytopenia may require hospitalization
Evaluate for underlying causes:
- Complete blood count with peripheral smear
- Liver function tests
- Coagulation studies (PT, PTT)
- Assessment for potential drug causes
- Evaluation for underlying systemic illness
Common Causes to Consider
Emergency Causes (Requiring Hospitalization):
- Heparin-induced thrombocytopenia (HIT)
- Thrombotic microangiopathies
- HELLP syndrome (Hemolysis, Elevated Liver enzymes, Low Platelets)
Non-Emergency Causes:
- Drug-induced thrombocytopenia
- Immune thrombocytopenia (ITP)
- Hepatic disease
- Infections
- Splenic sequestration
- Bone marrow disorders
Special Considerations
It's important to recognize that some thrombocytopenic conditions can present with both bleeding AND thrombosis, including:
- Antiphospholipid syndrome
- Heparin-induced thrombocytopenia
- Thrombotic microangiopathies 2
Treatment Approach
General Management:
- Treat underlying cause when identified
- Activity restrictions for patients with platelet counts <50 × 10³/μL to avoid trauma-associated bleeding 1
Platelet Transfusions:
- Recommended for active hemorrhage
- Recommended when platelet counts are <10 × 10³/μL
- Consider before invasive procedures to ensure adequate platelet counts 1
For Immune Thrombocytopenia (ITP):
- For adults with ITP who have had insufficient response to corticosteroids, immunoglobulins, or splenectomy, consider romiplostim 3
- For pediatric patients ≥1 year with ITP for at least 6 months with insufficient response to standard therapies, consider romiplostim 3
- Use the lowest dose of romiplostim to achieve and maintain platelet count ≥50 × 10⁹/L 3
- Initial dose: 1 mcg/kg subcutaneously weekly, with adjustments based on platelet count response 3
- Discontinue if platelet count doesn't increase sufficiently after 4 weeks at maximum dose (10 mcg/kg) 3
For Heparin-Induced Thrombocytopenia (HIT):
- Immediately discontinue all heparin products
- Switch to alternative anticoagulants
- Avoid platelet transfusions unless life-threatening bleeding or high-risk procedure is needed 2
- Monitor for thrombotic complications
Monitoring
- Weekly CBCs during dose adjustment phase of treatment
- Monthly CBCs after establishing stable treatment
- Weekly CBCs for at least 2 weeks following discontinuation of treatment 3
Pitfalls and Caveats
- Don't assume all thrombocytopenia is related to bleeding risk; some conditions (HIT, antiphospholipid syndrome) increase thrombotic risk
- Delayed-onset HIT can occur up to 3 weeks after heparin discontinuation 4
- Don't transfuse platelets in HIT patients except in life-threatening bleeding due to theoretical risk of exacerbating thrombosis 2
- Romiplostim should not be used to normalize platelet counts, only to reduce bleeding risk 3
- Romiplostim is not indicated for thrombocytopenia due to myelodysplastic syndrome or causes other than ITP 3