Why is fibrinogen low in Disseminated Intravascular Coagulation (DIC)?

From the Guidelines

Fibrinogen is low in Disseminated Intravascular Coagulation (DIC) because it is rapidly consumed during the widespread, inappropriate activation of the coagulation system that characterizes this condition. In DIC, a triggering event such as sepsis, trauma, or malignancy causes extensive activation of thrombin throughout the bloodstream, leading to the conversion of fibrinogen to fibrin, which forms microthrombi in small blood vessels throughout the body 1. As fibrinogen is continuously converted to fibrin during this process, its plasma levels become depleted. Simultaneously, the body's natural anticoagulant mechanisms become overwhelmed, and secondary fibrinolysis (the breakdown of fibrin clots) is activated, further contributing to fibrinogen depletion. This consumption of fibrinogen, along with platelets and other clotting factors, results in the paradoxical situation where patients experience both widespread clotting and severe bleeding tendencies.

Key Points

• Fibrinogen levels are depleted in DIC due to its conversion to fibrin, forming microthrombi in small blood vessels throughout the body.
• The depletion of fibrinogen is further exacerbated by secondary fibrinolysis, which breaks down fibrin clots.
• Laboratory findings typically show fibrinogen levels below 100 mg/dL, often alongside thrombocytopenia, prolonged prothrombin time, and elevated D-dimer levels, reflecting both the excessive clotting and subsequent fibrinolysis occurring in DIC 1.
• The management of DIC involves the use of platelet transfusion, fresh frozen plasma, and cryoprecipitate to maintain the platelet count and fibrinogen levels, and to prevent further bleeding complications 1.

Management of Low Fibrinogen in DIC

• Transfusion of two pools of cryoprecipitate or fibrinogen concentrate is suggested in actively bleeding cases with persistently low fibrinogen values (below 1.5 g L-1) despite supportive measures 1.
• The use of prothrombin complex concentrates may be considered in cases where concerns over volume overload exist 1.
• Frequent estimation of platelet count, fibrinogen, PT, and APTT is strongly recommended to monitor the patient's condition and adjust treatment accordingly 1.

From the Research

Fibrinogen Levels in Disseminated Intravascular Coagulation (DIC)

Fibrinogen levels are often low in patients with DIC due to several factors:

• Consumption of clotting factors, including fibrinogen, as a result of widespread activation of coagulation in the vasculature 2, 3
• Fibrinogen is converted into fibrin, which forms clots in the small blood vessels, leading to its depletion 4
• Hyperfibrinogenolysis, a condition characterized by excessive breakdown of fibrinogen, can also contribute to low fibrinogen levels in some cases of DIC 5

Clinical Implications

Low fibrinogen levels in DIC can increase the risk of bleeding, and severe hypofibrinogenemia (<1 g/l) may require treatment with fibrinogen concentrate or cryoprecipitate 2, 4

• The management of DIC involves treating the underlying condition, as well as controlling activation of blood coagulation and bleeding risk 3, 6
• Antifibrinolytic therapy, such as tranexamic acid, may be used in cases with severe bleeding or hyperfibrinogenolysis 5, 6

Diagnostic Challenges

DIC can be difficult to diagnose, as laboratory tests such as prothrombin time (PT) and activated partial thromboplastin time (APTT) may not always be abnormal 6

• A combination of clinical and laboratory information, including fibrinogen levels, is necessary to diagnose and manage DIC effectively 2, 3