Platelet Aggregation Test Accuracy with Platelet Count of 155
A platelet aggregation test with a platelet count of 155 × 10^9/L is likely accurate and does not require concentration to the standard range, as this count falls within acceptable parameters for reliable test results. 1
Understanding Platelet Count Requirements for Aggregation Testing
Platelet aggregation testing is affected by platelet count, but research has shown that adjustment of platelet count is not always necessary for accurate results:
- Light transmission aggregometry (LTA), considered the gold standard for platelet function testing, can produce reliable results with platelet counts in the normal range (150-450 × 10^9/L) 1
- A platelet count of 155 × 10^9/L is just above the lower limit of the normal range, making it acceptable for testing
Technical Considerations for Platelet Aggregation Testing
The International Society on Thrombosis and Haemostasis (ISTH) provides guidance on platelet aggregation testing:
- Thrombin generation increases linearly with platelet counts up to a plateau of 100-150 × 10^9/L 2
- A count of 155 × 10^9/L is above this threshold, suggesting adequate platelets for reliable testing
- For heparin-induced thrombocytopenia (HIT) testing using HIMEA protocol, standard donor blood is mixed with patient plasma without specific requirements for concentration when counts are in normal range 2
Evidence Supporting Non-Adjustment of Platelet Count
Research specifically addressing platelet count adjustment has found:
- Standardization studies have demonstrated that "adjustment of PRP for platelet count does not provide any advantage and therefore the time-consuming process of platelet count adjustment is not necessary" 1
- The variability of aggregation results can actually be higher in adjusted platelet-rich plasma compared to non-adjusted samples 1
When Platelet Count Adjustment May Be Needed
There are specific circumstances when platelet count adjustment might be considered:
- If the platelet count is significantly below normal (<100 × 10^9/L), results may be affected 2
- For specialized tests like thrombin generation assays, reporting thrombin generation per unit of platelets might be considered 2
- In research settings where standardization across multiple samples is critical 3
Quality Control Considerations
To ensure test accuracy with a platelet count of 155 × 10^9/L:
- Each test should be performed in duplicate with a coefficient of variation applied to each result 2
- Duplicate tests with >20% difference should be repeated 2
- If results are borderline or inconclusive, consider repeating the test with a fresh sample 2, 4
Conclusion
A platelet aggregation test with a platelet count of 155 × 10^9/L should provide accurate results without requiring concentration, as this count is within the acceptable range for testing. The evidence suggests that platelet count adjustment does not improve test accuracy and may actually increase variability in results.