The Causes of Death and Pathological Findings of Kratom Users: A 5-Year Retrospective Analysis.

Kratom is a psychoactive substance in Thailand. The major psychoactive chemical component of Kratom is mitragynine. This study aims to elucidate the characteristics and pathologies of autopsied cases where mitragynine was present and quantify the amounts of mitragynine. The autopsy reports in which the blood samples were positive for mitragynine were selected in Ramathibodi Hospital between January 2015 and December 2019. Data from autopsy reports comprised sex, age, circumstances of death, pathological findings, other substances, causes of death, and mitragynine concentrations. Mitragynine was quantitatively analyzed using liquid chromatography-mass spectrometry/mass spectrometry. Twenty-four cases from 2160 autopsy cases were found to be positive for mitragynine. The most commonly observed pathological findings were pulmonary edema (7 cases) and coronary atherosclerosis (6 cases). Antihistamine (8 cases), ethanol (4 cases), and amphetamine (4 cases) were commonly found. The mitragynine concentrations were 0.0035 to 3.6 mg/L (median 0.069). One interesting case involved a 43-year-old man whose pathological findings showed chronic asthma with a high concentration of mitragynine in the blood (3.6 mg/L), although no other substances were detected. In conclusion, the use of mitragynine may be a direct or indirect cause of death, whereas the lethal concentration has yet to be clearly determined.