Comparison of platelet counts in simultaneous venous and capillary blood samples using an automated platelet analyser

Area of Science:

• Hematology
• Clinical Pathology
• Medical Diagnostics

Background:

• Platelet counts (PC) from capillary blood (CB) are generally lower than those from venous blood (VB).
• Understanding this discrepancy is crucial for accurate patient assessment, especially in low platelet count (LPC) scenarios.

Purpose of the Study:

• To quantify the difference between venous blood (VB) and capillary blood (CB) platelet counts.
• To evaluate the reproducibility of platelet counts in patients with low platelet counts (LPC) and normal platelet counts (NPC).

Main Methods:

• Simultaneous collection of capillary blood (CB) and venous blood (VB) samples.
• Platelet counts were measured in 17 patients with LPC and 18 healthy volunteers with normal platelet counts (NPC).
• Statistical analysis included calculating mean differences and coefficients of variation (CV) to assess reproducibility.

Main Results:

• Venous platelet counts (VPC) were higher than capillary platelet counts (CPC) in 82.9% of cases (29/35).
• The mean difference between VPC and CPC was 9.4 x 10(3)/ul in LPC and 19.4 x 10(3)/ul in NPC.
• Reproducibility, assessed by CV, was poorer for both VPC and CPC in the LPC group compared to the NPC group.

Conclusions:

• Venous blood platelet counts are consistently higher than capillary blood counts.
• The agreement between venous and capillary platelet counts is poor in patients with low platelet counts.
• Capillary blood platelet counts exhibit lower reproducibility in patients with low platelet counts, potentially affecting clinical decisions.