Several mitochondria-related metabolites have been suggested as NAFLD markers: l-ornithine l-aspartate, citrulline/ornithine ratio, glutamine, glutathione, arginine, and glutamate [40]; and CPS-1 (carbamoyl phosphate synthase 1), OTC (Ornithine transcarbamoylase), FGF-21 (Fibroblast growth factor-21), and CK-18 (cytokeratin 18) [40,41]. Here, FGF21 is linked to metabolic dysfunction-associated steatotic liver disease.