Comparative evaluation of reagents for measuring protein S activity: possibility of harmonization

Masahiro Ieko, Taeko Hotta, Kumiko Watanabe, Tomoko Adachi, Sawako Takeuchi, Sumiyoshi Naito, Mika Yoshida, Kazumasa Ohmura, Nobuhiko Takahashi, Eriko Morishita, Hiroko Tsuda, Dongchon Kang

Research output: Contribution to journalArticlepeer-review


Patients with congenital protein S (PS) deficiency show a hereditary predisposition for thrombosis, and PS deficiency is prevalent among Japanese populations. Diagnosis is based on symptoms of thrombosis and reduced PS activity. Three reagents that use different measurement principles for determining PS activity are available in Japan. This study aimed to confirm the possibility of harmonization of these three reagents to establish a universal standard for PS activity in Japanese populations. Commercial normal plasma and plasma samples obtained from healthy individuals and healthy pregnant women were tested at three facilities using three reagents for measuring PS: STA-Staclot Protein S (STA-PS), HemosIL Protein S (Clotting) (IL-PS), and a total PS assay (SNT-PS). The within-run precision of each reagent was good, as each had a coefficient of variation of ≤ 3.8%. The dilution linearity for each reagent was also good. The correlation coefficient was 0.94 for STA-PS vs. IL-PS, 0.93 for SNT-PS vs. STA-PS, and 0.90 for SNT-PS vs. IL-PS, indicating a good correlation. Although the three reagents available in Japan for measuring PS activity use different measurement methods, each showed good performance, and large differences were not observed between the obtained values. Harmonization among them appears possible.

Original languageEnglish
JournalInternational journal of hematology
Publication statusAccepted/In press - 2021

All Science Journal Classification (ASJC) codes

  • Hematology

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