Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (403 page)

   Fibrinogen is useful when obtained serially, since it can demonstrate a dynamic process of consumption coagulopathy by its progressive decline.

   Platelet counts may be decreased, but thrombocytopenia is nonspecific. In cases of thrombocytopenia and thrombosis, HIT may have to be excluded.

   Best markers of hypercoagulability are elevated
D
-dimer. To avoid falsepositive results, a less sensitive assay, such as semiquantitative latex, is recommended rather than the ELISA-type supersensitive
D
-dimer tests used to rule out DVT and PE.

   The following assays are reproducible and have a high positive predictive value but are not available in most hospital laboratories: increased prothrombin fragments (F1 and F2), fibrinopeptides A and B, thrombin–antithrombin complexes, and soluble fibrin.

   Many clotting factors and the inhibitory proteins, protein C and S, are decreased because of their consumption. The most sensitive and undergoing highest decrease are factors V and VIII. Their determination is not necessary for the diagnosis of DIC.

   Because DIC is a microangiopathic syndrome, hemolytic anemia with schistocytes on the peripheral blood smear develops in severe cases.

   Laboratory evidence of organ failure is mandatory for the diagnosis and entails in most cases the typical chemistry profile of renal or other organ failure.

  2.  Fibrinolytic activation: Increased levels of fibrin(ogen) degradation products (FDP), latex
D
-dimer (see above). In primary fibrinolysis, FDP are greatly elevated, whereas
D
-dimers are not and platelet counts are normal.

  3.  Inhibitor consumption

   Progressive decrease in antithrombin (ATIII).

   Increased levels of thrombin–antithrombin and plasmin–antiplasmin.

   Decrease in α2 antiplasmin (not necessary for diagnosis).

Recommendations

   We have suggested a simple, selective “DIC profile” based on the three categories mentioned above: titration of latex
D
-dimer, FDP, and ATIII. Serial ATIII assays are useful for observing the evolution of the syndrome, since its marked decrease connotes a poor prognosis. FDP and
D
-dimers are elevated in chronic DIC as well. In addition to the above panel, chemistry panels to assess end-organ injury are mandatory.