title: Intrinsic hemostasis activation by freezing and thawing of plasma.
abstract: Low-grade contact activation of hemostasis is clinically relevant. Freezing/thawing of plasma was studied in the intrinsic coagulation activity assay. Normal plasmas were frozen at -80 degrees C or -20 degrees C and thawed at 37 degrees C or 23 degrees C. These plasmas and unfrozen samples were activated by SiO2 -CaCl2. Freezing/thawing of normal plasma induced about 100-fold more thrombin activity at 5 minutes coagulation reaction time than the respective unfrozen samples. Freezing at -80 degrees C induces more artificial changes than freezing at -20 degrees C. In 9 of 10 plasmas of patients receiving coumarin, nearly no additional thrombin is generated within a 12-minute coagulation reaction time. Minor procoagulant changes of plasma might be dangerous in patients with insufficient liver function, who might not tolerate a therapy with fresh frozen plasma, which behaves as a procoagulant because of its matrix changes. The intrinsic coagulation activity assay allows the measurement of low-grade contact activation of frozen/thawed plasma.
authors.affiliation: Department of Clinical Chemistry, University Hospital Giessen & Marburg, Germany. thstief@med.uni-marburg.de
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Stief
authors.forename: Stefanie
authors.initials: S
authors.lastname: Otto
authors.forename: Harald
authors.initials: H
authors.lastname: Renz
mesh_terms: D001780:Blood Coagulation Tests; D005615:Freezing; D006801:Humans; D019934:International Normalized Ratio; D010314:Partial Thromboplastin Time; D010949:Plasma / Q000737:chemistry*; D013696:Temperature