Understanding metabolic alterations in advanced stage chronic kidney disease patients by NMR-based metabolomics.

Understanding metabolic alterations in CKD is crucial, as serum creatinine-based diagnosis lacks precision, affecting key clinical decisions. In this study, a 1H NMR-based metabolomics approach was employed to distinguish between advanced-stage CKD (ASCKD) patients and healthy controls (HC), as well as within the ASCKD stages (stage 4 and stage 5). Serum samples from 52 ASCKD (S4, S5) and 25 HC were analyzed. Multivariate and univariate analysis revealed distinct metabolic patterns across groups, providing insights into CKD pathophysiology and associated pathway alterations. Compared to HC, six metabolites were significantly altered in both stage 4 and 5 CKD patients with upregulated creatinine, urea, myoinositol, choline, N,N-dimethylglycine, and downregulated tyrosine, showing potential as biomarkers with AUC above 0.8 in ROC analysis. Additionally, myo-inositol, dimethylamine, N,N-dimethylglycine, and choline correlate positively with creatinine while tyrosine correlates negatively. Amino acid metabolism was downregulated in S5 indicating more severity. Within ASCKD patients, significant alterations were observed in metabolites such as glutamate, glutamine, alanine, threonine, myo-inositol, dimethylamine, citrulline, urea, citrate, and betaine. Pathway analysis identified five distinct metabolic pathways associated with CKD progression. Consequently, we propose a panel of serum metabolites which should be monitored along with creatinine for following CKD progression. Markers of oxidative stress, inflammation, and gut dysbiosis were evident in the perturbed metabolic profile due to the systemic impact of CKD.