GPT and metabolic dysfunction-associated steatotic liver disease: The heatmap showed that children with MASLD + fibrosis had higher concentrations of methionine, leucine, glycine, alanine, proline, arginine, phenylalanine, ornithine, citrulline, carnitine, AC5:1, medium-chain acylcarnitine (AC6, AC8, and AC10:2), AC18, ALT, AST, and GGT than children with only MASLD (Figure 3a).