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Poster Networking

Coagulation Factors and Co-Factors

PB1127 - Effect of frozen storage conditions of Antithrombin, Protein C, Protein S activity assay stability

Tuesday, June 25, 2024
13:45 – 14:45 ICT
Room: Exhibition Hall

    Co-Author(s)

  • HF

    Houmei Feng

    Professor
    Department of Laboratory Medicine, Nanfang Hospital, Southern Medical University, Guangzhou, China
    Guangzhou, Guangdong, China (People's Republic)

    • Presenting Author(s)

  • Danyu Song, MM

    Doctor
    Department of Laboratory Medicine, National Center for Cardiovascular Disease, Chinese Academy of Medical Sciences & Peking Union Medical College Fuwai Hospital
    Beijing, Beijing, China (People's Republic)

    • Co-Author(s)

  • YZ

    Yang Zhang

    Professor
    Department of Laboratory Medicine, National Center for Cardiovascular Disease, Chinese Academy of Medical Sciences & Peking Union Medical College Fuwai Hospital
    Beijing, Beijing, China (People's Republic)

Background: Inherited antithrombin, protein C and protein S deficiency increase the risk of venous thromboembolism (VTE). The presence of deficiency can be determined by clinical laboratory assays. In most Chinese clinical laboratories, the screening tests of antithrombin, protein C and protein S deficiency are their activity assays. Appropriate pre-analytical storage conditions are essential for activity tests.

Aims: The aim of study was to assess the effects of storage conditions on antithrombin, protein C, protein S activity in frozen plasma.

Methods: We collected the remaining sodium-citrate-anticoagulated (citrate concentration is 3.2%) plasma of 30 first-admitted patients routine coagulation tests. The antithrombin, protein C, protein S activity assay were completed within 4 hours of collection. This value served as a baseline. Then, each plasma was subpackaged into 4 EP tubes. Two aliquots were frozen at -20℃ and other two aliquots were frozen at -80℃ at stable temperature, two fridges without auto-defrost mechanism. After 3 days and 7 days, frozen plasma specimens had been rapidly thawed at 37℃, then gently mixed and tested immediately.

Results: The percentage deviation of antithrombin and protein C activity assay was＜10% compared with the initial values. Protein S activity showed a prominent reduction at -20℃ or -80℃ in 3 days and 7days. The percentage deviation of Protein S activity assay was significant > 10% from the baseline values which detected in 4 hours after venipuncture. We argued that Protein S activity was not stable when using the specimen had been frozen.Some samples that are normal at baseline are classified to be abnormal after freezing storage.

Conclusion(s): Our study indicated that antithrombin and protein C are stable when stored at -20℃ or -80℃ in a week. Protein S activity was not stable when using the plasma had been frozen.The use of frozen-thawed plasma for PS activity assay may result in overdiagnosis of protein S deficiency.