Expert consensus regarding standardization of sample preparation for clotting time assays

Area of Science:

• Laboratory Hematology
• Clinical Chemistry

Background:

• Accurate clotting time assay results are essential for prescribing oral anticoagulants and diagnosing hemorrhagic/thrombotic diseases.
• Sample preparation procedures, including centrifugation, significantly impact clotting time assay outcomes.
• Variability in results necessitates standardized methods for preparing patient blood samples.

Purpose of the Study:

• To establish a standardized method for preparing blood samples for clotting time assays.
• To provide consensus-based guidelines for optimal sample handling and processing.
• To improve the reliability and reproducibility of clotting time test results.

Main Methods:

• A Working Group for Standardization of Sample Preparation for Clotting Time Assays (WG) was formed by the Japanese Society of Laboratory Hematology.
• The WG reviewed existing guidelines and original experimental data.
• Consensus was reached on key parameters for sample preparation.

Main Results:

• Recommended anticoagulant: sodium citrate solution at 0.105–0.109 M (3.13–3.2%).
• Whole blood storage: at room temperature (18–25 °C) within 1 hour of collection.
• Centrifugation for plasma: 1500 × g for ≥15 min or 2000 × g for ≥10 min at room temperature.
• Plasma sample handling: store at room temperature and assay within 4 hours.

Conclusions:

• Standardized protocols for blood sample preparation are vital for accurate clotting time assays.
• Adherence to recommended anticoagulant concentration, storage, centrifugation, and assay timing ensures reliable results.
• These guidelines aim to enhance clinical decision-making in anticoagulant therapy and disease management.