What is the role of global clotting times and coagulation factors in the workup of disseminated intravascular coagulation (DIC)?

Updated: Dec 06, 2020
  • Author: Marcel M Levi, MD; Chief Editor: Srikanth Nagalla, MBBS, MS, FACP  more...
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Answer

Global clotting times (ie, activated partial thromboplastin time [aPTT] and prothrombin time [PT]) are typically prolonged. In as many as 50% of DIC patients, however, a normal or even an attenuated PT and aPTT may be encountered; consequently, such values cannot be used to exclude DIC. [57] This phenomenon may be attributed to certain activated clotting factors present in the circulation, such as thrombin or Xa, which may in fact enhance thrombin formation. [33]

It should be emphasized that serial coagulation tests are usually more helpful than single laboratory results in establishing the diagnosis of DIC. It is also important to note that the PT, not the international normalized ratio (INR), should be used in the DIC monitoring process; INR is recommended only for monitoring oral anticoagulant therapy. [39]

The prolongation of global clotting times may reflect the consumption and depletion of various coagulation factors, which may be further substantiated by the measurement of selected coagulation factors, such as factor V and factor VII. Measurement of coagulation factors may be helpful for detecting additional hemostatic abnormalities (eg, those caused by vitamin K deficiency).

Protein C and antithrombin are 2 natural anticoagulants that are frequently decreased in DIC. There is some evidence to suggest that they may serve roles as prognostic indicators. [58, 59] Nonetheless, the practical application of measuring these anticoagulants may be limited for most practitioners because the tests may not be generally available. [39]

DIC is associated with an unusual light transmission profile on the aPTT, known as a biphasic waveform. In one study, the degree of biphasic waveform abnormality had an increasing positive predictive value for DIC, independent of clotting time prolongation. [60] In addition, the waveform abnormalities are often evident before more conventionally used laboratory value derangements, [60] making this a quick and robust test for DIC. At present, however, the photo-optical analyzers necessary in clot formation analysis are not widely available.


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