D-dimer is a prognostic marker for Covid-19 disease mortality and severity in hospitalized patients;however, little is known about the association between D-dimer and other clinical outcomes The aim of this paper was to define a threshold of D-dimer to use in hospitalized patients with Covid-19 and to assess its utility in prognosticating in-hospital mortality, development of an acute kidney injury (AKI), and need for hemodialysis, vasopressors, or intubation This is a single-center, retrospective, cohort review study of 100 predominantly minority patients (94%) hospitalized with Covid-19 The electronic medical record system was used to collect data Receiver operating characteristics (ROC) and area under the curve (AUC) analysis were used to determine optimal thresholds of peak D-dimer, defined as the highest D-dimer obtained during admission that was clinically meaningful Odds ratios were then used to assess the relationship between peak D-dimer thresholds and clinical outcomes D-dimer > 2 1 μg/mL and > 2 48 μg/mL had > 90% sensitivity and > 50% specificity for predicting need for vasopressors (AUC 0 80) or intubation (AUC 0 83) and in-hospital mortality (AUC 0 89), respectively Additionally, D-dimer > 4 86 μg/mL had a 100% sensitivity and 81% specificity for predicting the need for hemodialysis (AUC 0 92) Furthermore, peak D-dimer > 2 48 μg/mL was associated with in-hospital mortality (p 2 48 μg/mL may be a useful threshold that is prognostic of multiple clinical outcomes in hospitalized patients with Covid-19