Thomas Lee Ortel, MD, PhD

Professor of Medicine
Chief, Division of Hematology in the Department of Medicine
Professor of Pathology
Member of the Duke Cancer Institute
Campus mail 0563 Stead Bldg, Durham, NC 27710
Phone (919) 684-5350
Email address

My research program investigates the molecular mechanisms whereby various congenital and acquired abnormalities result in ‘dysfunctional’ hemostasis (i.e., hemorrhage or thrombosis) to better understand the molecular mechanisms and interactions that are necessary for normal hemostasis. We are particularly interested in the mechanisms whereby antibodies and other inhibitors can interfere with normal hemostatic mechanisms. Several projects extensively overlap and focus on the assembly and function of procoagulant (e.g., factor X-ase and prothrombinase) and anticoagulant (e.g., activated protein C complex) phospholipid membrane-dependent complexes.

We utilize a variety of approaches in these studies. Monoclonal antibodies, single-chain variable domain fragments, polyclonal antibodies prepared from patients with factor VIII inhibitors, and site-specific mutagenesis have all been used to characterize structure-function relationships in coagulation factor VIII. Our laboratory has also extensively characterized anti-factor V antibodies, investigating autoantibodies as well as xenogenic antibodies developing after exposure to topical bovine thrombin preparations which contain trace amounts of contaminating bovine factor V. We have also characterized how antiphospholipid antibodies interfere with the activated protein C complex, a lipid-dependent natural anticoagulant complex that proteolytically inactivates factor Va and factor VIIIa.

Our current studies are focusing on two antibody-mediated thrombotic syndromes, heparin-induced thrombocytopenia and antiphospholipid antibody syndrome. First, we are initiating a large clinical trial investigating the incidence of clinically-significant heparin-induced thrombocytopenia in patients who develop anti-heparin/platelet factor 4 antibodies following cardiac bypass procedures. While these antibodies are commonly seen following cardiac bypass, the true incidence of thromboembolic complications related to these prothrombotic antibodies remains unknown. We are also collaborating with investigators in the Center for Human Genetics on a large, multi-center study exploring the genetics of familial antiphospholipid antibody syndrome. In addition, we have used a genomic strategy to investigate patients with antiphospholipid antibody syndrome and have identified a gene expression profile that appears to be unique to patients with this syndrome in contrast to patients with venous thromboembolism who do not have these autoantibodies.

We also participate in a variety of collaborative research efforts, both with individual investigators as well as participating in multi-center clinical research studies. For example, we are one of seventeen centers participating in the NIH-supported Transfusion Medicine/Hemostasis Network, and we are currently conducting a trial through this network to define the optimal dose of platelets for patients needing platelet transfusions for hypoproliferative thrombocytopenia. We are also part of a multi-center registry of patients with thrombotic thrombocytopenic purpura, and we are one of eight centers in the Hemostasis and Thrombosis Center pilot program sponsored by the Centers for Disease Control and Prevention. Participation in these registries and networks provides us with access to the patient populations that we study in the research laboratory.

In Their Words

Education and Training

  • Fellow in Hematology-Oncology, Medicineq, Duke University, 1988 - 1991
  • Medical Resident, Medicine, Duke University, 1985 - 1988
  • M.D., Indiana University at Indianapolis, 1985
  • Ph.D., Indiana University at Bloomington, 1983


Root, A. G., R. D. Raiff, T. L. Ortel, and K. L. Hodulik. “Initiation of Emicizumab Therapy in an Adult Patient With Hemophilia A With Inhibitors and Associated Drug Cost Savings.” Journal of Pharmacy Technology 36, no. 3 (June 1, 2020): 110–13.

Full Text

Khatib, Rasha, Stephanie Ross, Sean Alexander Kennedy, Ivan D. Florez, Thomas L. Ortel, Robby Nieuwlaat, Ignacio Neumann, et al. “Home vs hospital treatment of low-risk venous thromboembolism: a systematic review and meta-analysis.” Blood Adv 4, no. 3 (February 11, 2020): 500–513.

Full Text

Refaai, Majed A., Grace Conley, Thomas L. Ortel, and John L. Francis. “Evaluation of a rapid and automated heparin-induced thrombocytopenia immunoassay.” In Int J Lab Hematol, 41:478–84, 2019.

Full Text

Hashmi, Nazish K., Kamrouz Ghadimi, Amudan J. Srinivasan, Yi-Ju Li, Robert D. Raiff, Jeffrey G. Gaca, Adam G. Root, et al. “Three-factor prothrombin complex concentrates for refractory bleeding after cardiovascular surgery within an algorithmic approach to haemostasis.” Vox Sang 114, no. 4 (May 2019): 374–85.

Full Text

Ortel, Thomas L., Katie Arnold, Michele Beckman, Audrey Brown, Nimia Reyes, Ibrahim Saber, Ryan Schulteis, Bhavana Pendurthi Singh, Andrea Sitlinger, and Elizabeth H. Thames. “Design and Implementation of a Comprehensive Surveillance System for Venous Thromboembolism in a Defined Region Using Electronic and Manual Approaches.” Appl Clin Inform 10, no. 3 (May 2019): 552–62.

Full Text

Streiff, Michael B., Bjorn Holmstrom, Dana Angelini, Aneel Ashrani, Paula L. Bockenstedt, Carolyn Chesney, John Fanikos, et al. “NCCN Guidelines Insights: Cancer-Associated Venous Thromboembolic Disease, Version 2.2018.” J Natl Compr Canc Netw 16, no. 11 (November 2018): 1289–1303.

Full Text

Devreese, K. M. J., T. L. Ortel, V. Pengo, and B. de Laat. “Laboratory criteria for antiphospholipid syndrome: reply.” J Thromb Haemost 16, no. 10 (October 2018): 2117–19.

Full Text

Onwuemene, Oluwatoyosi A., Steven C. Grambow, Chetan B. Patel, Robert J. Mentz, Carmelo A. Milano, Joseph G. Rogers, Ara D. Metjian, Gowthami M. Arepally, and Thomas L. Ortel. “Indications for and outcomes of therapeutic plasma exchange after cardiac transplantation: A single center retrospective study.” J Clin Apher 33, no. 4 (August 2018): 469–79.

Full Text