Fig. 4

Enhanced volcano plots showing significantly changed metabolites. a Serum and b urine samples. Volcano plot shows − log₁₀ (P-value) on the y-axis versus log₂ (fold change) on the x-axis. Each point represents a different metabolite. The circles size and colour are determined based on the variable importance projection (VIP) and absolute correlation coefficient values (|r|), respectively. For each comparison, VIP values are categorized into two categories: top 30% and remaining 70%, with each represented by large and small circles, respectively. A warmer colour corresponds to higher |r|