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/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.