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May 2020 Quick Question: D-dimer Results

Our May, 2020 Quick Question, which attracted 70 responses, was, “What assay does your lab use to monitor DIC?” The answers were somewhat predictable, only with a twist. They were:

a. FDP: 1% [1]
b. D-dimer: 69% [48]
c. FDP & D-dimer: 30% [21]
d. Other, please comment: 0

These findings are interesting because most North American labs have switched over to exclusive use of D-dimer. Still available is ThermoFisher’s time-honored semiquantitative Thrombo-Wellcotest latex agglutination test, mostly used in under-resourced or near-patient testing circumstances. This question arose as George found that many Covid-related studies from China and elsewhere reported both D-dimer and FDPs, and it turns out that in China and other countries, FDP is available as an automated procedure. When performed together, the results parallel each other. On a June 2, 2020 follow-up call, Dave McGlasson notes that FDP is not used in the ISTH DIC score. From our poll, we don’t know how many respondents are from China or other locations that perform both assays.

The thrombotic mechanism in advanced Covid infection remains an open discussion. It is clear that the D-dimer and FDP assays are consistently elevated, but PT and PTT prolongation are modest and hyperfibrinogenemia is a predictable acute inflammatory marker. There are few reports of thrombocytopenia. Is it venous thromboembolic disease? Platelet activation that generates arterial thrombosis? Thrombotic microangiopathy? Full-blown DIC? Hypofibrinolysis?

A descriptive study, Wright FL, Vogler TO, Moore EE, et al. Fibrinolysis shutdown correlates to thromboembolic events in severe COVID-19 Infection, JACS, May 14, 2020. DOI: [click or tap] uses a combination of Thromboelastograph [TEG] fibrinolysis results [LY 30] and D-dimer to predict the need for mechanical ventilation and renal dialysis. Those who evidence NO fibrinolysis and a D-dimer of >2600 FEUs have an 80% likelihood of requiring renal dialysis.

George attempts to stay current with the flood of Covid-hemostasis publications as medical scientists move towards a conclusion that leads to effective treatment. If you see anything interesting, please pass it along to [email protected].

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