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Coumarin Plant Poisoning Workup

  • Author: Arasi Thangavelu, MD, FACEP, FAAEM; Chief Editor: Asim Tarabar, MD  more...
Updated: Mar 31, 2014

Laboratory Studies

See the list below:

  • Obtain complete blood count, prothrombin time (PT) (expected to be normal if obtained shortly after ingestion), and International Normalized Ratio (INR).
    • Serial PTs at 24 and 48 hours postingestion should identify patients at risk of coagulopathy
    • The World Health Organization introduced INR in an effort to standardize the results of the PT test. Values of INR are independent of the reagents and methods and, therefore, are comparable between laboratories across the country and abroad. The INR is defined as the normal PT ratio that would result if the World Health Organization's primary international thromboplastin were used to test the patient's sample. INR = (Patient PT/ normal PT) ISIISI is the International Sensitivity Index of the thromboplastin used in the local laboratory.
  • A high performance liquid chromatographic method can be used to detect and quantify serum levels of the following 5 anticoagulant rodenticides: brodifacoum, bromadiolone, coumatetralyl, difenacoum, and warfarin. Warfarin and superwarfarin levels may be obtained; however, these specialized tests generally are not helpful in the ED setting.
  • In cases of surreptitious hydroxycoumarin use, vitamin K-2, -3 epoxide and vitamin K can be measured. Elevated levels of vitamin K-2, -3 epoxide suggest block of reductive step by a hydroxycoumarin.
  • Fresh frozen plasma provides active anticoagulation factors in patients with significant active bleeding.
  • Type and crossmatch packed red cells in patients with hemodynamic compromise or significant blood loss.

Imaging Studies

If intracranial hemorrhage is suspected, consider CT scan of the head.

Contributor Information and Disclosures

Arasi Thangavelu, MD, FACEP, FAAEM Consulting Staff, Department of Emergency Medicine, Archbold Memorial Hospital

Arasi Thangavelu, MD, FACEP, FAAEM is a member of the following medical societies: American Academy of Emergency Medicine, Emergency Medicine Residents' Association, American College of Emergency Physicians

Disclosure: Nothing to disclose.


Lisandro Irizarry, MD, MPH, FACEP Chair, Department of Emergency Medicine, Wyckoff Heights Medical Center

Lisandro Irizarry, MD, MPH, FACEP is a member of the following medical societies: American Academy of Emergency Medicine, American College of Emergency Physicians, American College of Medical Toxicology, Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

Specialty Editor Board

John T VanDeVoort, PharmD Regional Director of Pharmacy, Sacred Heart and St Joseph's Hospitals

John T VanDeVoort, PharmD is a member of the following medical societies: American Society of Health-System Pharmacists

Disclosure: Nothing to disclose.

Chief Editor

Asim Tarabar, MD Assistant Professor, Director, Medical Toxicology, Department of Emergency Medicine, Yale University School of Medicine; Consulting Staff, Department of Emergency Medicine, Yale-New Haven Hospital

Disclosure: Nothing to disclose.

Additional Contributors

B Zane Horowitz, MD, FACMT Professor, Department of Emergency Medicine, Oregon Health and Sciences University School of Medicine; Medical Director, Oregon Poison Center; Medical Director, Alaska Poison Control System

B Zane Horowitz, MD, FACMT is a member of the following medical societies: American College of Medical Toxicology

Disclosure: Nothing to disclose.


Michael Hodgman, MD Assistant Clinical Professor of Medicine, Department of Emergency Medicine, Bassett Healthcare

Michael Hodgman, MD is a member of the following medical societies: American College of Medical Toxicology, American College of Physicians, Medical Society of the State of New York, and Wilderness Medical Society

Disclosure: Nothing to disclose.

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