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Teachable Moment
June 24, 2019

Coagulation Testing in Patients Taking Direct Oral Anticoagulants: A Teachable Moment

Author Affiliations
  • 1Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas
  • 2Division of Hematology Oncology, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas
  • 3Division of Hematology Oncology, Department of Medicine, VA North Texas Health Care System, Dallas
JAMA Intern Med. 2019;179(9):1274-1275. doi:10.1001/jamainternmed.2019.1799

A 55-year-old man with a history of atrial fibrillation, hypertension, and type 2 diabetes mellitus presented to the emergency department (ED) with abdominal pain and vomiting for 1 day after eating leftover salad. His medications included rivaroxaban, amlodipine, and metformin. Results from physical examination were unremarkable. The patient’s comprehensive metabolic panel and complete blood cell count revealed no significant abnormalities. Abdominal radiograph to rule out small bowel obstruction was within normal limits. The patient received 2 L of normal saline with resultant symptomatic improvement. The diagnosis of gastroenteritis was made with plans to discharge the patient.

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2 Comments for this article
The Abnormal INR
PAUL FUCHS, M.D. | Solo independent Family Physician
In this particular non elderly individual with normal renal and hepatic function and one day of vomiting, why was the INR 7.1? Even though it may be related to the rivaroxaban, the timing of his last dose, and the test characteristics, can that abnormal result simply be dismissed because the INR should never have been checked? Possibly it was fortuitous that the INR was inappropriately ordered.
DOAC mysteries
Joerg Wiesenfeldt, MD | Verbundkrankenhaus Bernkastel-Wittlich
Indeed, an INR of 7.1 seems highly unusual. Should we really question our lab routines ? Or could we leave the one-size-fits-all approach to DOAC dosing and request further testing with an anti-Xa-assay, peak and through ? Perhaps switching the odd "7.1 patient" to some milder, less bleeding-prone anticoagulant ?
Thank you very much for this very interesting observation !