Effects of Tourniquet Technique, Order of Draw, And Sample Storage on Plasma Fibrinogen (Technical Briefs‪)‬

The use of plasma fibrinogen concentrations to predict clinical ischemic events in subjects with and without prior evidence of atherosclerosis [1-14] has led to recommendations to incorporate fibrinogen into the cardiovascular risk profile [15]. Such use of plasma fibrinogen requires careful attention to potential sources of variability, as only small (5%) absolute differences in fibrinogen distinguish subjects who develop cardiovascular disease from those subjects who do not [16]. Variability in fibrinogen results apart from intraindividual differences is difficult to quantify, because the few groups who have examined these issues used different assays for fibrinogen determination. Moreover, the functional assay for fibrinogen is highly influenced by technician expertise and manipulation [17]. Previously, we examined within-run analytical CV, within-person, within-day biological variation, and a 6-week within-person biological variation with the Clauss method for fibrinogen determination [16].