AbstractAn elderly man with decreased kidney function was admitted to hospital with gastrointestinal bleeding. After remaining stable for 2 days in hospital, he became haemodynamically unstable and an adverse effect of dabigatran was suspected, but efforts to treat the patient failed and the following morning he passed away. In conjunction with the autopsy, blood samples from his hospital stay were analysed for dabigatran, revealing the highest concentration (6400 ng/mL) apparently reported to date. Supra‐therapeutic dosing was, however, never suspected. Dabigatran is largely excreted through the kidneys. A possible cause of the high dabigatran concentrations could be a rapid decrease in kidney function that seemingly occurred over a period of 2 months, sometime between his initiation of treatment (eGFR 51–55 mL/min/1.73 m2) and subsequent hospital admission (eGFR 31 mL/min/1.73 m2). The increasing dabigatran concentrations in the patient was, however, not apparent to the prescribing doctor, as therapeutic drug monitoring of dabigatran is not recommended in current guidelines and no such analyses were performed. There may be a need to evaluate blood concentrations of dabigatran, in the light of the reported differences in interindividual concentrations, along with the increased risks of thromboembolic events with lower concentrations and major bleeding events with higher concentrations. Functional assays to assess concentrations of dabigatran in blood have been developed and are available in some hospitals to be used in suspected overdoses or before emergency surgeries. Methods to determine concentrations of dabigatran specifically have also been developed and can additionally be used for therapeutic drug monitoring in an outpatient setting, especially in high‐risk individuals.