Rapid estimation of fibrinogen in fibronlytic and nonfibrinolytic states.

Anticoagulated whole blood is serially diluted in a fibrinolytic inhibitor, then clotted with thrombin after adding calcium chloride. The clotting end point, visualized by addition of saline, is related to the concentration of clottable protein present. Protection of the forming clot against lysis is afforded by the inhibitor, by calcium chloride, and by the brief incubation at room temperature, and enables blood fibrinogen concentration to be readily discernible, even if it is less than 25 mg/100 ml. Fibrinogen in the blood is quickly estimated irrespective of the patient’s clinical status.