RBP4 and metabolic dysfunction-associated steatotic liver disease: To investigate the association of urinary RBP/creatinine ratio with NAFLD, we stratified subjects into quartiles according to their urinary RBP/creatinine ratio levels (< 0.13 mg/g, 0.14-0.23 mg/g, 0.24-0.46 mg/g, > 0.46 mg/g).