Heparin-induced thrombocytopenia with thrombosis in COVID-19 adult respiratory distress syndrome

Early reports of coronavirus disease 2019 (COVID-19) clinical features describe a hypercoagulable state, and recent guidelines recommend prophylactic anticoagulation for patients with COVID-19 with low-molecular-weight heparin, but this would be contraindicated in the presence of heparin-induced thrombocytopenia (HIT). We address the key clinical question whether HIT is also present during COVID-19. We report 3 cases of thrombocytopenia with antiplatelet factor 4 antibodies among 16 intubated patients with COVID-19 with adult respiratory distress syndrome, a higher-than-expected incidence of 19%. Each patient had evidence of thrombosis (pulmonary embolism, upper extremity venous thromboses, and skin necrosis, respectively). The serotonin release assay confirmed HIT in 1 case, and 2 cases were negative. We believe this is the first reported case of HIT during the COVID-19 pandemic. Recognition that the thrombocytopenia represented HIT in the confirmed case was delayed. We recommend clinicians monitor platelet counts closely during heparin therapy, with a low threshold to evaluate for HIT.