Higher serum trimethylamine N-oxide (TMAO) levels are associated with increased visceral fat in hemodialysis patients

Background: Trimethylamine N-oxide (TMAO), a gut microbiota-derived metabolite, has emerged as a new potentially important cause of increased atherosclerosis and cardiovascular risk in chronic kidney disease (CKD) patients. However, the possible causes whereby TMAO potentiates atherosclerosis development remain poorly defined. The strong association between gut microbiota and obesity suggested that the TMAO pathway may be linked to the pathogenesis of obesity. Materials and methods: A total of 184 hemodialysis (HD) patients and 38 healthy controls were enrolled in the study from March 2019 to May 2019. We evaluated visceral fat area (VFA) by anthropometric measurement and measured serum TMAO concentrations using liquid chromatography/differential ion mobility spectrometry tandem mass spectrometry. We also examined the relationship between TMAO levels and visceral fat accumulation. Results: TMAO level was markedly higher in HD patients than in control subjects (5.80 (3.96, 9.46) vs. 0.18 (0.11, 0.32) mu g/mL, p < 0.01), and its level in diabetic HD patients was significantly higher than in non-diabetic patients (6.93 (4.67, 11.40) vs. 5.25 (3.78, 8.02) mu g/mL, p < 0.01). A significant positive correlation was found between se-rum TMAO level and VFA in these patients (r = 0.282, p = 0.005). Multiple regression analysis showed that Ln(TMAO) was independently associated with Ln(VFA) in HD patients (p = 0.008). Conclusion: Our results showed that there was a significant positive correlation between serum TMAO levels and visceral fat in HD patients, which suggested that TMAO may predict cardiovascular risk through increased visceral fat.