Cause of Thrombocytosis in Empyema
Secondary thrombocytosis in empyema is caused by megakaryocytic hyperplasia in the bone marrow as part of the inflammatory response to infection, with platelet counts typically peaking around 2 weeks after illness onset and returning to normal after approximately 3 weeks. 1
Pathophysiology of Thrombocytosis in Empyema
Thrombocytosis in empyema follows a specific pattern:
- Occurs as a reactive process to the severe bacterial infection
- Characterized by bone marrow megakaryocytic hyperplasia 2
- Platelet counts typically exceed 500 × 10^9/L in over 90% of children with empyema 1
- Platelet counts reach maximum levels at approximately 15 days (range 7-25 days) after illness onset 2
- Counts gradually return to normal after about 3 weeks of illness 1
Clinical Significance
Secondary thrombocytosis in empyema is a benign condition despite sometimes dramatic elevations in platelet counts 1
Platelet function remains normal despite elevated counts 2
No correlation exists between thrombocytosis and:
- Fever severity
- Neutrophilia
- Clinical course
- Complications
- Prognosis or treatment response 2
Thrombocytosis can be a distinguishing biomarker for severe pyogenic infections, especially empyema 3
In community-acquired pneumonia, thrombocytosis is associated with:
- Higher likelihood of complicated pleural effusion and empyema
- Longer hospital stays
- Higher 30-day mortality rates 4
Management Implications
- No specific treatment is required for the thrombocytosis itself 1
- Antiplatelet therapy is unnecessary despite sometimes dramatically elevated platelet counts 1
- No reports of thrombotic complications have been found in studies of children with secondary thrombocytosis 1
- Treatment should focus on the underlying empyema with appropriate antibiotics and drainage procedures 1
Monitoring
- Regular monitoring of platelet counts is reasonable until resolution
- Platelet counts typically normalize spontaneously as the underlying infection resolves 2
- Persistent thrombocytosis beyond 3-4 weeks may warrant further investigation for ongoing infection or other causes 1
Important Distinctions
- Secondary thrombocytosis in empyema should be distinguished from primary thrombocytosis (essential thrombocythemia), which would require specific hematologic evaluation 5
- The presence of thrombocytosis in pneumonia should prompt consideration of empyema as a complication 4
Caveat
While thrombocytosis in empyema itself doesn't require specific treatment, its presence may indicate a more severe infection requiring aggressive management of the underlying empyema with appropriate antibiotics, drainage procedures, and possibly fibrinolytics or surgical intervention 1, 4.