Stress-induced alterations in coagulation: assessment of a new hemoconcentration correction technique.

Objective: For the examination of psychological stress effects on coagulation, the Dill and Costill correction (DCC) for hemoconcentration effects has been used to adjust for stress-induced plasma volume changes. Although the correction is appropriate for adjusting concentrations of various large blood constituents, it may be inappropriate for time-dependent or functional coagulation assays. Two new plasma reconstitution techniques for correcting hemoconcentration effects on stress-induced changes in coagulation were compared with the DCC.

Methods: Blood was collected from 31 men during baseline, the Trier Social Stress Test (TSST), and after 20-minute recovery. For the reconstitution techniques, TSST plasma samples were reconstituted with either baseline plasma or physiological saline equal to the amount of plasma lost during stress.

Results: Uncorrected activated partial thromboplastin time (APTT) decreased, whereas fibrinogen, factor VIII clotting activity (FVIII:C), D-dimer and prothrombin time (PT%) increased significantly during the TSST. The DCC produced a significantly greater decrease in APTT during stress compared to uncorrected APTT, a significant decrease in PT% compared to uncorrected PT%, and stress D-dimer and fibrinogen and FVIII:C being no different than baseline. APTT, fibrinogen, D-dimer and PT% after saline reconstitution were not different from baseline, whereas FVIII:C after saline reconstitution remained elevated. APTT, PT%, fibrinogen and D-dimer after plasma reconstitution were no different from uncorrected values, whereas FVIII:C remained significantly elevated.

Conclusions: The observed changes in coagulation are likely in part a consequence of stress and hemoconcentration, but the DCC seems to be an inappropriate hemoconcentration correction technique of time-dependent assays. The saline reconstitution technique may be more biologically relevant when examining stress-hemoconcentration effects on coagulation.