Hematological and clinical-chemistry parameters of kratom users: a comparative study of users and non-users in Southern Thailand

Abstract

Kratom (Mitragyna speciosa) has transitioned from a traditional Southeast Asian remedy to a substance of global interest. The existing evidence on its safety is contradictory, with case reports from Western countries suggesting organ toxicity, while community-based studies in traditional settings show minimal adverse effects. This study aimed to evaluate the physiological impact of long-term, traditional kratom use in an endemic region of Southern Thailand. A cross-sectional study was conducted among 285 traditional kratom users and 296 non-user controls from the same community. Key hematological and clinical-chemistry parameters, including liver and kidney function markers, were compared. Analyses were stratified by sex and kratom use characteristics (duration and quantity) to assess subgroup-specific effects. Analysis of Covariance (ANCOVA) was used to adjust for potential confounding variables, including age, sex, BMI, smoking, and alcohol consumption. After adjusting for confounders, no clinically significant differences were observed in hepatic or hematological parameters, with mean values for both groups remaining within normal clinical reference ranges. However, kratom use was significantly associated with lower serum creatinine (p < 0.001) and higher eGFR (p = 0.002), a finding likely attributable to the lower BMI in the user group. Stratified analyses by duration and quantity revealed no clear dose–response relationship regarding organ toxicity, although higher consumption was associated with altered renal markers. These findings suggest that within a traditional-use setting, chronic kratom consumption was not associated with clinically significant hepatic or hematological toxicity. The observed association with renal markers is explained by differences in body composition rather than a direct pharmacological effect. These findings underscore the critical importance of controlling for lifestyle and demographic confounders in evaluating the health impacts of kratom.