Background: Only few pediatric reports exist regarding the prevalence, cause and evolution of liver and renal injury in patients with anorexia nervosa (AN). The aim of this study is to describe the prevalence and the risk factors of hepatic and renal failure at admission and during hospitalization, especially during refeeding in a cohort of hospitalized adolescents with AN.Methods: In a retrospective cohort study of adolescents with AN in a single hospital of Marseille from 2013 to 2019, we compared four groups on admission: elevated aminotransferases (AT)/normal AT and renal injury/no renal injury to analyze the differences between them (demographic factors, anthropometric factors, disease duration, initial prescribed calories, speed of refeeding, aminotransferase level, glomerular filtration rate). We observed the evolution of AT and renal injury for these four groups during refeeding (by the increase of kilocalories). Results: A total of 29 subjects with AN met eligibility criteria (age: 14.2 years, female (86.2%), BMI at admission (Z-score= -2.8 standard deviation (SD)) with elevated AT (20.7 %) and renal injury (13.8 %) on admission. Lower Z-score BMI (-4.05 vs -2 SD, p = 0.013), lower expected weight for height (69% vs 76%, p = 0.034) and longer disease duration (2.1 vs 0.9 years, p =0,032) were significantly associated with elevated liver enzymes at admission. Lower Z-score BMI (-3.35 vs -2.5 SD, p = 0.002), lower expected weight for height at admission (69% vs 74,5%, p = 0.002) and loss of weight before admission (0.66 vs à 0.20 kg per day, p = 0.002) were associated with renal injury at admission. Time nadir BMI (13.5 vs 6.5 days, p = 0.034) and duration of hospitalization (55 vs 41 days, p = 0.036) were longer in elevated enzymes on admission group. During refeeding, liver enzymes (95% confidence interval (CI), odds ratio (OR) aspartate aminotransferase: -0.07 [-0.11; -0.03] and OR alanine aminotransferase: -0.16 [-0.27; -0.06]) and renal injury (95% CI, OR creatinine: -0.013 [-0.017; -0.008]) have normalized with the increase of calories, with significant association.Conclusions: The results of this study suggest that degree of malnutrition is associated with liver and renal injury on admission. Theses failures disappeared with refeeding. In the future, prospective multicentric studies could examine evolution of renal and hepatic failure undergoing refeeding in large pediatric cohort of AN.