Neutrophil-to-Lymphocyte Ratio Reflects Hepatic and Nutritional Recovery in Hospitalized Patients With Anorexia Nervosa

Objective: This study aims to investigate changes in the neutrophil-to-lymphocyte ratio (ΔNLR) during inpatient nutritional rehabilitation and to examine its associations with nutritional and hepatic recovery in patients with anorexia nervosa (AN). Materials and methods: We retrospectively reviewed the medical records of female inpatients aged <20 years admitted for AN at two psychiatric departments in Nara, Japan, between April 2010 and October 2023. Body mass index (BMI) and biochemical parameters were assessed within one week of admission and prior to discharge. NLR was calculated as the ratio of neutrophil to lymphocyte counts. ΔBMI and ΔNLR were defined as the differences between admission and discharge values. Statistical analyses included Wilcoxon signed-rank tests, Spearman’s rank correlation, and multiple linear regression. Results: BMI increased significantly during hospitalization, as did NLR. At discharge, BMI was negatively correlated with NLR. Lower baseline BMI predicted a greater increase in BMI, whereas higher baseline NLR predicted a greater increase in NLR. ΔNLR were associated with hepatic enzyme dynamics, characterized by increased aspartate aminotransferase (AST) and decreased alanine aminotransferase (ALT), and by the ΔAST/ΔALT ratio, indicating coordinated improvements in hepatic and immune function. Conclusions: NLR increases in parallel with nutritional and hepatic recovery during inpatient treatment for AN. These findings suggest that NLR may serve as a simple and cost-effective biomarker reflecting systemic physiological restoration beyond weight gain alone.