The presence of D-dimer in the blood plasma

D-dimer

D-dimer is one of the protein fragments produced when a blood clot gets dissolved in the body. It is normally undetectable or detectable at a very low level unless the body is forming and breaking down blood clots. Then, its level in the blood can significantly rise. This test detects D-dimer in the blood.

Why is D-dimer measured?

The presence of D-dimer in the blood plasma, which has a half-life of roughly 8 hours until kidney clearance occurs, is often used as a clinical biomarker to identify thrombotic activity and therefore diagnose conditions like pulmonary embolism (PE), deep vein thrombosis (DVT), venous thromboembolism (VTE) and disseminated intravascular coagulation (DIC).

Growing importance of Ddimer diagnostics in COVID19 patients

Fact The COVID-19 pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is still spreading across many parts of the world, and clinicians are working on recognizing biomarkers that are of value in predicting the risk of mortality in each case so as to make appropriate clinical decisions. This is also necessary for designing clinical studies and assessing the outcome of various novel treatments. Now, a new study published on the preprint server medRxiv* reports the use of D-dimer in predicting the risk of mortality in COVID-19.

• Inflammation the relationship between peripheral blood levels of D-dimer, and clinical classification and prognosis, as well as its related influencing factors. D-dimer levels were found to be related to the clinical classification and the prognosis of clinical outcome. D-dimer levels were more likely to be abnormal in severely and critically ill patients compared with mild and ordinary cases, while D-dimer levels of patients who had died were significantly higher than those of surviving patients according to the results of the first and last lab tests.
• D-dimer is a product of cross-linked fibrin, it is considered a sensitive biomarker to rule out venous thromboembolism. However, D-dimer has low specificity as there are many other conditions with ongoing activation of the hemostatic system in which D-dimer can be elevated such pregnancy, inflammation, malignancy, trauma, liver disease (decreased clearance), heart disease, sepsis or as a result of hemodialysis, CPR or recent surgery.

The results from ROC analyses for mortality risk showed that the AUCs of D-dimer were 0.909, YI was 0.765 at the last lab test, and a D-dimer value of 2.025 mg/L was regarded to be the optimal probability cutoff for a prognosis of death.

In addition, it was found that patients with advanced age, male gender, dyspnea symptoms, and some underlying diseases have a higher D-dimer value (p < 0.05). In short, D-dimer is related to the clinical classification and can be used to evaluate the prognosis of COVID-19 patients.

The D-dimer value of 2.025 mg/L was the optimal probability cutoff for judging an outcome of death. Advanced age, male gender, dyspnea symptoms, and some underlying diseases are influencing factors for D-dimer levels, which impacts the prognosis of patients.

Levels of ddimer increasing. Several different studies have looked to measure D-dimer levels in hospitalized COVID-19 patients to determine whether this biomarker could be useful in predicting patient outcomes. In one study conducted in China between January 31 and February 12, 2020, the biological characteristics of a total of 274 COVID-19 patients with a median age of 62 were analyzed.

Of the 113 patients who did not survive, it was reported that their D-dimer levels were higher at a median of 4.6 µg/mL, whereas the surviving 161 patients had D-dimer levels that averaged at 0.6 µg/mL.

Similar results were reported in another study conducted in China between January 1 and February 13, 2020. In this work conducted by Tang et al., the D-dimer levels of 134 deceased COVID-19 patients averaged at 4.7 µg/ml, whereas 315 patients who had survived following severe COVID-19 effects had median D-dimer levels of 1.47 µg/ml.

Although these data indicate that D-dimer testing, in combination with the analysis of other biomarkers, can be of assistance during the treatment of COVID-19 patients, further studies must be performed to fully validate the role that D-dimer testing can have in the decision-making process.

Young or non-sever patients dying of strokes/heart attacks.

It is estimated that 10-15% of COVID-19 patients will experience critical forms of this disease that progress to severe pneumonia, hypoxia, and respiratory failure, all of which will require supportive care and supplemental nasal oxygen.

Furthermore, about 5% of these severe COVID-19 cases have been found to decline even further to acute respiratory distress syndrome (ARDS) or multiple organ failure (MOF), both of which require intensive care unit (ICU) admittance with mechanical ventilation or extracorporeal membrane oxygenation (ECMO).

Despite the widespread cases and severe forms of COVID-19 that have been reported, there remains a limited understanding as to why certain individuals develop ARDS and MOF and others do not.

To improve the early identification of these severe forms of COVID-19, many researchers have committed themselves and their teams to identify reliable biomarkers.

References

• Linkins, L. A., & Lapner, S. T. (2017). Review of D-dimer testing: Good, Bad, and Ugly. International Journal of Laboratory Hematology 39(51). doi:10.1111/ijlh.12665.
• Palta, S., Saroa, R., & Palta, A. (2014). Overview of the coagulation system. Indian Journal of Anaesthesia 58(5); 515-523. doi:10.4103/0019-5049.144643.
• Weitz, J. I., Fredenburgh, J. C., & Eikelboom, J. W. (2017). A Test in Context: D-Dimer. Journal of the American College of Cardiology 70(19); 2411-2420. doi:10.1016/j.jacc.2017.09.024.
• World Health Organization. What we know about long-term effects of COVID-19. World Health Organization. Available from: https://www.who.int/docs/default-source/coronaviruse/risk-comms-updates/update-36-long-term-symptoms.pdf

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