Analysis Note

Protein determined by biuret

Application

Fibrinogen has been used in studies of haemostatic therapy in surgical and massive trauma patients. These studies have shown that fibrinogen may prove to be more superior in stopping blood loss when compared to using fresh frozen plasma (FFP).

Biochem/physiol Actions

Fibrinogen is an acute phase protein that is part of the coagulation cascade of proteins. The end result of the cascade is the production of thrombin that converts fibrinogen to fibrin. Thrombin rapidly proteolyzes fibrinogen, releasing fibrinopeptide A. The loss of this small peptide is not sufficient to make the resulting fibrin molecule insoluble, but it tends to form complexes with adjacent fibrin and fibrinogen molecules. Thrombin then cleaves a second peptide, fibrinopeptide B, from fibrin and the fibrin monomers formed then polymerize spontaneously to form an insoluble gel. The polymerized fibrin is held together by noncovalent and electrostatic forces and stabilized by the transamidating enzyme, factor XIIIa, that is produced by the action of thrombin on factor XIII. The insoluble fibrin aggregates (clots) and aggregated platelets then block the damaged blood vessel and prevent further bleeding. The amount of fibrinogen in the plasma can serve as a nonspecific indicator of whether or not an inflammatory process is present in the body. Fibrinogen from any mammalian source will be cleaved by thrombin from any mammalian source.

Packaging

1, 5, 10, 25, 100 g in poly bottle

Physical form

Contains ~10% sodium citrate and ~15% sodium chloride.

Reconstitution

The optimal way to solubilize fibrinogen is to layer it on top of warm (37 ºC) saline, as fibrinogen will not dissolve in water. The saline concentration can be in the range of 0.85-0.9%. The fibrinogen-saline solution can be gently agitated, but it must not be vortexed. The fibrinogen will slowly dissolve to give a hazy solution. Fibrinogen may be sterile-filtered, but may not go through a 0.1 µm filter. A 0.2 µm filter is suggested, with positive pressure using a syringe and "button" filter. Vacuum filtration should not be used, since this will lead to breakdown of the molecule during the filtration.