Can D-dimer be Used as a Marker for Thromboembolic Events in Pediatric Patients With COVID-19?

D-dimer is a protein resulting from fibrin degradation. It is released into the circulation when clot degradation occurs and is therefore used as a marker for thromboembolic events and fibrinolysis. The main role of D-dimer lies in its negative predictive value for the exclusion of thromboembolic events, when its level is below 500 ng/mL. Because D-dimer functions as an inflammatory marker, various non-thromboembolic situations can contribute to an increase in its level, such as advanced age, pregnancy, postpartum period, neoplasms, renal insufficiency, and sepsis. Age is a crucial factor when considering D-dimer a thromboembolic marker. Healthy populations over 70 years of age have shown a 50% increase in D-dimer levels without correlation with thrombotic or inflammatory events.

During the COVID-19 pandemic, several studies have demonstrated a positive correlation of elevated D-dimer levels, prolonged coagulation time, and low platelet count with mortality from COVID-19.^,,,Although D-dimers lack high specificity as a diagnostic tool, they have been widely used as predictors of severity and complications in this setting, given that D-dimer tests are rapid, simple, and low-cost.^– However, hyperinflammation caused by SARS-CoV-2 infection can lead to an increase in D-dimer unrelated to thrombosis, which implies its correlation with other tests and caution in interpreting the results.

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