Serum Trimethylamine N-Oxide Levels as a Predictor of Peripheral Arterial Disease in Kidney Transplant Recipients

BACKGROUND Trimethylamine N-oxide (TMAO), a gut-derived uremic toxin, is linked to hypertension, cardiovascular events, and mortality. Peripheral arterial disease (PAD), defined by a low ankle-brachial index (ABI), increases mortality in kidney transplantation (KT) recipients. This study investigated the association between serum TMAO levels and PAD in KT recipients. MATERIAL AND METHODS This cross-sectional study included 98 KT recipients. Serum TMAO levels were quantified using liquid chromatography-mass spectrometry, and ABI values were assessed with an automated oscillometric device. Patients with ABI <0.9 were categorized as having PAD. Additional clinical and laboratory data were collected from medical records for analysis. RESULTS Among 98 KT recipients, 22 (22.4%) had low ABI values. The low-ABI group had higher serum TMAO levels (P<0.001) and a higher diabetes prevalence (P=0.035). In multivariate analysis, serum TMAO levels were independently associated with PAD (odds ratio: 1.154, 95% CI: 1.062-1.255, P=0.001). Both the left and right ABI values were negatively correlated with TMAO levels (P<0.001). In the Spearman correlation analysis, the estimated glomerular filtration rate (eGFR) was negatively correlated with TMAO levels (P=0.005). The area under the receiver operating characteristic curve for TMAO predicting PAD was 0.868 (95% CI: 0.784-0.928, P<0.001). CONCLUSIONS Elevated serum TMAO levels are independently associated with PAD in KT recipients, as evidenced by their significant negative correlation with ABI values. These findings suggest that TMAO may serve as a potential biomarker for identifying KT recipients at higher risk of PAD.