Sarcopenia and Fat Mass in Children With Chronic Liver Disease and Its Impact on Liver Transplantation

**Background:** Sarcopenia (loss of muscle mass) is a key feature of cachexia in chronic diseases including cirrhosis. In children with end-stage chronic liver disease (ESCLD), standard anthropometric measures like weight are confounded by hepatosplenomegaly and fluid retention. Adult literature shows that loss of lean mass predicts poor outcomes in liver transplantation (LT), but pediatric data are limited. This study tested whether sarcopenia in children with ESCLD is associated with poor post-LT outcomes and whether changes in fat mass occur in tandem with lean mass changes.

**Methods:** Children aged 4–18 years with ESCLD undergoing LT assessment were prospectively recruited. Exclusion criteria included acute liver failure, liver tumors, and inborn errors of metabolism. Anthropometry (weight, height, mid-upper arm circumference, BMI) was converted to SD scores (SDS) using UK WHO reference data. Whole-body dual-energy x-ray absorptiometry (DXA) scans provided total and regional body composition. Fat mass index (FMI) and lean mass index (LMI) were calculated and converted to SDS. Sarcopenia was defined as arm or leg LMI SDS below −1.96 (2.5th centile). Laboratory parameters including APRI (marker of portal hypertension) and neutrophil-to-lymphocyte ratio (marker of systemic inflammation) were recorded. Transplanted children had repeat DXA approximately 1 year post-LT. Statistical analysis used parametric/nonparametric tests as appropriate, with significance at P<0.05.

**Key Results:** Eleven children (6 female, 5 male; median age 9.9 years, range 4.7–17.2) were assessed at baseline. Diagnoses included biliary atresia (n=3), Alagille syndrome (n=2), and others. Nine children underwent LT. At baseline, mean weight SDS was −0.67, mean height SDS was −1.00, and mean BMI SDS was −0.04. All fat mass and FMI SDS values were above −1.96 (within normal range). Four patients (36%) were sarcopenic (appendicular LMI SDS < −1.96). There was a strong negative correlation between total FMI SDS and height SDS at baseline (correlation −0.75; P<0.05). APRI had a significant positive correlation with trunk LMI SDS (correlation 0.66; P=0.03). The neutrophil-to-lymphocyte ratio had a significant negative correlation with arm FMI SDS (correlation −0.63; P=0.04). After transplant (mean 1.12 years post-LT), there was a significant reduction in trunk LMI SDS from 1.20 to −0.51 (Δ=1.7; 95% CI 1.03–2.4; P<0.01). Appendicular LMIs improved but not significantly. Arm FMI SDS increased significantly (Δ=−0.69; 95% CI −1.10 to −0.31; P<0.01). Mean days to discharge post-LT was 25 days (median 16, range 10–80). BMI SDS correlated negatively with days to discharge (R=0.73; R²=0.53; P<0.05). Of patients staying >16 days, 66.7% were sarcopenic vs. 22.2% of those discharged within 16 days. At 1 year, all transplanted patients were alive with normal graft function regardless of pre-LT body composition.

**Clinical Implications:** This study demonstrates that sarcopenia is common (36%) in children with ESCLD, yet fat mass is preserved even in sarcopenic patients, suggesting a metabolic prioritization of fat storage over lean mass. The strong inverse correlation between FMI and height SDS indicates that more stunted children have higher fat mass, possibly reflecting energy conservation at the expense of linear growth. The significant reduction in trunk LMI post-transplant likely reflects resolution of organomegaly rather than true muscle loss, underscoring the importance of using appendicular (not trunk) measures to assess sarcopenia in CLD. The association between higher BMI SDS and shorter hospital stay raises the hypothesis that improving nutritional status to increase fat mass might improve short-term post-LT outcomes, though this requires confirmation in larger studies. Longer follow-up is needed to assess metabolic consequences including obesity and metabolic syndrome in this population.