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Case Report: Abnormal Fluctuation of International Normalized Ratio Due to Laboratory Errors and Drug Interactions

12 Pages Posted: 25 Sep 2023 Publication Status: Preprint

See all articles by Haohui Liu

Haohui Liu

Guangzhou University of Chinese Medicine

Yanhui Jiang

Guangzhou University of Chinese Medicine

Jie Huang

Guangzhou University of Chinese Medicine

Xiaowei Han

Guangzhou University of Chinese Medicine

Tong Wu

Guangzhou University of Chinese Medicine

Wenjie Long

Guangzhou University of Chinese Medicine

Xiaojiao Zhang

Guangzhou University of Chinese Medicine

Zhongqi Yang

Guangzhou University of Chinese Medicine

Abstract

Background: Warfarin, a widely-used anticoagulant for thrombotic event management, can lead to overanticoagulation due to various factors. In patients with markedly elevated international normalized ratio (INR) on warfarin, practitioner often focus on medication changes and dietary influences, but inadvertently overlook the coagulation function report’s credibility.

Case information: We present a patient whose INR rapidly exceeded the detectable range after warfarin and ceftriaxone/tazobactam use, with subsequent challenges in correction. The patient experienced nosebleeds and extensive subcutaneous bleeding, and INR gradually returned to normal after multiple interventions. Retrospectively, the patient adjusted warfarin dosage without monitoring INR, posing overdose risk. The mismatch between INR and activated partial thromboplastin time (APTT) suggests possible laboratory errors contributing to the rapid INR increase. Additionally, potential warfarin-ceftriaxone/tazobactam interactions could cause recurring mild INR increases.

Conclusion: Evaluating coagulation function in warfarin patients necessitates assessing report credibility. INR-APTT correlation effectively confirms reliability. Healthcare professionals must be aware of the report’s credibility and this specific interaction, particularly when managing elderly patients with multiple complications and medications. Considering report credibility, close patient monitoring, and avoiding potential interacting drugs can minimize adverse event risk.

Note:

Funding Information: We would like to clarify that this research did not receive any external funding or financial support. It was conducted as part of routine clinical and academic activities without specific grant or sponsorship.

Conflict of Interests: None to declare

Ethical Approval: The studies were reviewed and approved by Medical Ethics Committee of the First Affiliated Hospital of Guangzhou University of Chinese Medicine. Seven months after the patient was released from the hospital, we contacted the patient for a followup and obtained informed consent.

Keywords: case report, coagulopathy, warfarin, antibiotic, laboratory errors

Suggested Citation

Liu, Haohui and Jiang, Yanhui and Huang, Jie and Han, Xiaowei and Wu, Tong and Long, Wenjie and Zhang, Xiaojiao and Yang, Zhongqi, Case Report: Abnormal Fluctuation of International Normalized Ratio Due to Laboratory Errors and Drug Interactions. Available at SSRN: https://ssrn.com/abstract=4574891 or http://dx.doi.org/10.2139/ssrn.4574891

Haohui Liu

Guangzhou University of Chinese Medicine ( email )

Guangzhou
China

Yanhui Jiang

Guangzhou University of Chinese Medicine ( email )

Guangzhou
China

Jie Huang

Guangzhou University of Chinese Medicine ( email )

Guangzhou
China

Xiaowei Han

Guangzhou University of Chinese Medicine ( email )

Guangzhou
China

Tong Wu

Guangzhou University of Chinese Medicine ( email )

Guangzhou
China

Wenjie Long

Guangzhou University of Chinese Medicine ( email )

Guangzhou
China

Xiaojiao Zhang

Guangzhou University of Chinese Medicine ( email )

Guangzhou
China

Zhongqi Yang (Contact Author)

Guangzhou University of Chinese Medicine ( email )

Guangzhou
China

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