Correlation between serum trimethylamine-N-oxide concentration and protein energy wasting in patients on maintenance hemodialysis

OBJECTIVES: Chronic kidney disease (CKD) is a serious health problem that is associated with several systemic changes, including protein energy wasting (PEW). However, the exact mechanism of PEW in CKD remains unclear. As one of the important intestinal flora metabolites and uremic toxins, trimethylamine-N-oxide (TMAO) is involved in CKD-associated mortality, which might play a role in the development of PEW in CKD patients especially in patients on maintenance hemodialysis (MHD). However, this possibility has not been investigated. METHODS: PEW was diagnosed in a group of CKD patients on MHD according to the criteria of the International Society of Renal Nutrition and Metabolism. Serum TMAO concentration was assessed by high-performance liquid chromatography and mass spectrometry. The association between TMAO concentration and PEW was assessed using linear regression and logistic analysis after adjustment for confounding factors, including basic characteristics, comorbidities, and laboratory findings. RESULTS: The circulating TMAO level was higher in the MHD patients than in control (healthy) individuals (5653.76 ± 2853.51 vs. 254.92 ± 197.88 ng/mL, p < 0.001). Further, after the MHD patients were screened for PEW, those with PEW were found to have significantly higher serum TMAO levels than those without PEW (6760.9 vs. 4016.1 ng/mL, p < 0.001). Further, the serum TMAO concentration exhibited a significant negative correlation with body mass index (BMI) and dietary protein intake. In the logistic regression analysis, after adjustment for confounding factors, the serum TMAO concentration was still significantly correlated with PEW occurrence. CONCLUSIONS: The circulating TMAO level is significantly correlated with the prevalence of PEW in MHD patients. TMAO might be a potential target in the prevention and treatment of PEW in CKD especially ESRD.