ABSTRACT
Disseminated intravascular coagulation (DIC) is characterized by activation of hemostasis
and fibrinolysis resulting in the formation of thrombin and plasmin, and the characteristic
effects of these enzymes on plasma fibrinogen can be useful in diagnosis. Thrombin
cleaves fibrinopeptides from fibrinogen, forming fibrin monomer that rapidly polymerizes
to form a clot. Small amounts can circulate in plasma as ``soluble fibrin,'' which
may have a complex composition and include fibrinogen and a variable amount of cross-linking.
Plasmic degradation of cross-linked fibrin forms a heterogeneous group of degradation
products reactive in assays for D-dimer, and their levels provide a measure of the
amount of fibrin formation and lysis. Caution should be exercised in comparing quantitative
results using different assays because of problems with standardization and variable
reactivity with different molecular forms. Marked elevations of fibrin(ogen) degradation
products are a constant finding in experimental animal models of DIC. In human models
of DIC resulting from endotoxin infusion, D-dimer is elevated early and high levels
persist, reflecting lysis of microvascular fibrin deposits. Elevated levels of D-dimer
and soluble fibrin are very sensitive for the diagnosis of DIC, and a normal level
has a high negative predictive value. Serial monitoring of soluble fibrin or D-dimer
assays may be of value in evaluating the response to therapy and possibly in identifying
at-risk patients.
KEYWORD
Fibrin(ogen) degradation products - D-dimer - soluble fibrin - disseminated intravascular
coagulation - DIC - endotoxin
