Fibrinolysis and COVID-19: a tale of two sites?

We thank Tang et al. for their perspective on the possible limitation of D-dimer levels guiding anticoagulant treatment in patients with COVID-19 [1]. Although there is a clear association with elevated D-dimer and severity of COVID-19 disease, it is important to highlight the fact that D-dimer has always been utilised in conjunction with clinical pre-test probability, as a predictive tool to help exclude a possible diagnosis of venous thromboembolism. It has never been validated to guide clinical treatment or anticoagulation. It has recently been noted that a significant proportion of the recent literature concerning D-dimer in COVID-19 is fraught with variable, poor or incomplete reporting which further muddies its role in the management of COVID-19 related coagulopathy[2].