Normal Platelet Count Range
The normal platelet count range is 150,000 to 400,000 platelets per microliter (μL) of blood. 1, 2
Standard Reference Values
- Normal range: 150,000-400,000 platelets/μL 1, 2
- In pediatric populations, the normal range is typically cited as 250,000-450,000 platelets/μL 3
- Platelet counts are measured using automated cell counters, which are accurate even at low platelet counts, though modest variations can occur due to technological limitations 4
Clinical Significance of Deviations
Thrombocytopenia (Low Platelet Count)
Mild thrombocytopenia is defined as platelet counts below 150,000/μL but above critical thresholds 1
Critical thresholds for bleeding risk:
- Major bleeding is unusual unless platelet count falls below 5,000/μL in clinically stable patients 5
- Approximately 7,100 platelets/μL/day are randomly consumed in maintaining vascular integrity 5
- The most significant predictor of bleeding is not the absolute platelet count but rather a history of bleeding in the prior 5 days 5
Thrombocytosis (Elevated Platelet Count)
Thrombocytosis is defined as platelet count >450,000/μL (>2 standard deviations above normal) 3
Clinical classification of thrombocytosis severity in children: 3
- Mild: 500,000-700,000/μL
- Moderate: 700,000-900,000/μL
- Severe: >900,000/μL
- Extreme: >1,000/μL
Important Clinical Context
Platelet count alone is a weak indicator of hemostatic function because it provides no information about platelet dysfunction 4. Severe injury can result in platelet activation and dysfunction even with normal platelet counts, which has been associated with increased mortality 4.
The normal therapeutic platelet production rate is approximately 100 billion (10^11) platelets per day to maintain steady-state counts 2.