TriniCLOT Fibrinogen
TriniCLOT Fibrinogen is intended for quantitative determination of fibrinogen in plasma.
Fibrinogen is the plasma protein precursor of fibrin, which when cross-linked, becomes the
principal component of the fibrin clot. Thrombin cleaves fibrinogen to form a fibrin monomer.
Fibrin monomers aggregate to form the insoluble fibrin polymers. Fibrinogen can be deficient
in such conditions as congenital afibrinogenemia, hypofibrinogenemia and in some cases of
dysfibrinogenemia. It can also be depressed in a number of disease states such as
disseminated intravascular coagulation, systemic fibrinolysis, pancreatitis and severe hepatic
dysfunction. Fibrinogen is an acute phase reactant protein whose concentration increases in
response to many different physiological stimuli. It can be increased as a response to
inflammatory states, with infections, during pregnancy and after trauma. It is elevated among
smokers.1,2 High fibrinogen levels in plasma have been associated with prethrombotic states.
Fibrinogen levels have also been positively correlated to development of atherosclerotic
cardiovascular disease and with the occurrence of myocardial infarction and stroke.3,4
Because of the increased importance of the assessing fibrinogen levels, a reliable, sensitive
procedure is necessary.
Most methods for determining fibrinogen concentration rely on the assumption that thrombin
will quantitatively convert fibrinogen to fibrin. Estimation of concentration based on the
weight or protein content of the formed fibrin clot may be subject to large errors due to the
presence of inhibitors which cause little or no clot to form. Plasmin can also produce
significant lysis of the formed clot before the final fibrinogen determination can be
completed. Alternate procedures based on ammonium sulfate precipitation have been
described5,6 but do not correlate with thrombin clotting times when fibrinogen levels are
below 100 mg/dl (1.0 g/L).7
The determination of biologic activity (i.e. clottability) is more useful in diagnosis than is
the quantity of circulating fibrinogen. The method of Clauss8 measures the rate of fibrinogen
to fibrin conversion in the presence of excess thrombin and has been shown to be rapid,
sensitive and precise.9,10 The procedure described here is based on the Clauss method.
When diluted plasma is clotted with excess thrombin, the fibrinogen level is inversely
proportional to the clotting time, yielding a curvilinear relationship when plotted on log-log
paper. A calibration curve prepared from a fibrinogen reference is used to determine the
fibrinogen concentration in the test sample.
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