A prothrombin time-based functional assay of protein S

L. Preda, A. Tripodi, C. Valsecchi, A. Lombardi, E. Finotto, P. M. Mannucci

Research output: Contribution to journalArticlepeer-review


Protein S activity was measured as the degree of prolongation of a prothrombin time-based clotting assay in which diluted test sample, protein S-depleted plasma previously incubated with Protac to fully activate protein C, bovine thromboplastin and calcium ions are mixed. Assay specificity was first demonstrated by observing that the prolongation of the clotting time was dependent on protein S and was subsequently confirmed by testing plasma samples from patients with conditions known to affect protein S activity. High sensitivity, reproducibility (interassay coefficient of variation lower than 5%) and easy handling of samples and reagents make this assay suitable for screening of congenital and acquired protein S deficiency.

Original languageEnglish
Pages (from-to)19-32
Number of pages14
JournalThrombosis Research
Issue number1
Publication statusPublished - Oct 1 1990


  • laboratory screening
  • protein S
  • thrombophilia

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine
  • Hematology


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