The Fibrinogen Functional Turbidimetric Assay

Abstract

Hitherto, clinical fibrinogen methods were based on coagulation seconds, with assay conditions not similar to a plasma milieu. The fibrinogen functional turbidimetric assay included 50 µL citrated plasma + 100 µL 300 mIU/mL thrombin, 400 µg/mL polybrene, and 6% albumin—phosphate-buffered saline; an increase in absorbance at 405 nm/5 min at room temperature (or 2 minutes at 37°C) was observed. In all, 6% albumin in the fibrinogen functional turbidimetric assay reagent abolishes falsely elevated fibrinogen to fibrin turbidity in hypoproteinemic plasma samples. This assay can detect fibrinogen activity of 250% to 300% of normal, the lower detection limit being 7% of normal (0.2 g/L). The normal range of this assay is 100% ± 20% (mean value ± 1 SD; coefficient of variations <4%). This assay imitates fibrinogen to fibrin conversion in clotting blood plasma; it is independent of plasmatic albumin or heparin and can be performed everywhere. This assay has a diagnostic value in pathology-disseminated intravascular coagulation and in assessing risk for atherothrombosis.