Extremely elevated international normalized ratio in a patient using dabigatran etexilate: a case report

In general, blood coagulation tests are not necessary in patients using non-vitamin K-dependent oral anticoagulants (NOACs) [1,2]. If the patient follows the prescribed indications for NOACs, adjusting the dosage or administration interval of the medication according to the changes in coagulation tests is not necessary [3]. Here, we present the case of a patient with nonvalvular atrial fibrillation (NVAF) who was taking dabigatran and showed an extremely elevated prothrombin time-international normalized ratio (PT-INR). Background: We present the case of a patient who was administered dabigatran and showed an extremely elevated prothrombin time-international normalized ratio (PT-INR). Case Report: A 79-year-old man was referred due to PT-INR 12.6. The patient was taking 110 mg of dabigatran twice daily in capsule form. On admission, blood urea nitrogen level was 23 mg/dL, creatinine was 1.51 mg/dL, and the estimated glomerular filtration rate was 44.8 mL/min/1.73 m 2 . Coagulation tests revealed PT 96.8 seconds, PT-INR 12.46, and activated partial thromboplastin time 125.5 seconds. Dabigatran was discontinued, PT-INR on the day after admission was 8.96. PT-INR recovered to 1.61 on the fourth day without any treatment. Conclusion: The PT-INR was not directly correlated with dabigatran activity. Regular monitoring of coagulation was not necessary in all patients taking dabigatran. However, it may be useful to regularly perform coagulation tests in patients with renal impairment or in those at a high risk of bleeding.