Tests for DIC.

Q In my laboratory, we are suddenly getting quite a few requests for disseminated intravascular coagulation-(DIC) related testing. We currently do prothrombin time (PT), partial thromboplastin time (PTT), fibrinogen (FIB), D-dimer, and CBC. Based on my experience in a coag lab a few years ago, I am suggesting fibrin monomer as additional testing. Would this be helpful, or is our current testing adequate?

A The Scientific Subcommittee (SSC) on Disseminated Intravascular Coagulation of the International Society on Thrombosis and Haemostasis (ISTH) published a definition of DIC as well as clinical and laboratory criteria for diagnosis in the December 2001 issue of Thrombosis and Haemostasis. In this publication, the Subcommittee distinguished overt DIC from non-overt DIC. The Subcommittee defined overt DIC as that which occurs in a decompensated hemostatic system and non-overt as a compensated phase in which there is subtle hemostatic dysfunction.

In an effort to standardize diagnosis and determination of the severity of DIC, the ISTH Subcommittee on DIC has developed a five-step diagnostic algorithm that can be used to calculate a DIC score. A five-year overview of this scoring system was published on behalf of the SSC on DIC of the ISTH in the March 2007 issue of Thrombosis and Haemostasis and concluded that a score of five or greater can identify overt DIC. The diagnostic algorithm for the diagnosis of overt DIC is provided in Table 1.

In this report, it was stressed that assays used in the diagnosis of overt DIC should be readily available laboratory tests. According to the ISTH Subcommittee on DIC, major laboratory criteria for the diagnosis of overt DIC include platelet count, prothrombin time, fibrinogen level, and a marker of the presence of fibrin, which can be ascertained by one of the following assays: soluble fibrin monomer, fibrin degradation products, and/or D-dimer. In the 2003 meeting of the SCC on DIC, D-dimer was proposed as the ideal fibrin marker.

Therefore, the following battery of assays, PT/FIB/D-dimer/CBC, should be adequate in the evaluation of overt DIC, without the inclusion of a fibrin monomer assay. This is advantageous, as there is currently no manufactured kit available in the United States for the quantitation of soluble fibrin monomer. Diagnostica Stago offers a rapid qualitative slide test for soluble fibrin monomer complexes in plasma by the hemagglutination technique (F.S. Test). (1) This assay, however, is not as sensitive to the presence of fibrin monomers in plasma as a quantitative immunologic-based soluble fibrin monomer assay.

--Dorothy M. Adcock, MD

Esoterix

Aurora, CO

References

1. F.S. Test [package inser]. Parsippany, NJ: Diagnostica Stago; October 2003.

2. Toh CH, Hoots WK. The scoring system of the Scientific and Standardization Committee on Disseminated Intravascular Coagulation of the International Society on thrombosis and haemostasis: a 5-year overview. J Thromb Haemost. 2007;5:604-606.

3. Taylor FB, Toh CH, Hoots WK, et al. Towards definition, clinical and laboratory criteria, and a scoring system for disseminated intravascular coagulation. Thromb Haemost. 2001;86:1327-1330.

4. Minutes from the Scientific Subcommittee on Disseminated Intravascular Coagulation (DIC) of the International Society on Thrombosis and Haemostasis. July 2003, Birmingham, U.K. Hoots WK, Chairman.

Table 1. Diagnostic algorithm for the diagnosis of overt DIC (2-4)

Risk assessment: Does the patient have an underlying disorder known to
  be associated with over DIC? If yes, proceed; if no, do not use this
  algorithm;
Order global coagulation tests
Score global coagulation results
platelet count (>100 = 0; <100 = 1; <50 = 2)
elevated fibrin-related marker (e.g., D-dimer, soluble fibrin monomers/
  fibrin degradation products) (no increase: 0; moderate increase: 2;
  strong increase: 3)
prolonged prothrombin time (<3 sec. = 0; >3 sec. but <6 sec. = 1; >6
  sec. = 2)
fibrinogen level (>1.0 gram/l = 0; <1.0 gram/l = 1)
Calculate score
If [greater than or equal to] 5: compatible with overt DIC; repeat
  scoring daily if <5: suggestive (not affirmative) for non-overt DIC;
  repeat next one to two days.