[Bioimpedance analysis parameters and metabolic profile in children with non- alcoholic fatty liver disease]

Non-alcoholic fatty liver disease (NAFLD) in children is considered a manifestation of metabolic disturbances, that is a complex of interrelated alterations in carbohydrate and lipid metabolism associated with insulin resistance and an increased proportion of visceral fat. In this context, a comprehensive assessment of metabolic parameters combined with body composition analysis in children with NAFLD and without it is relevant for clarifying the role of visceral obesity in the development and progression of the disease, as well as for improving the accuracy of clinical assessment. The aim of the research was to assess the characteristics of the metabolic profile and bioimpedance analysis (BIA) parameters and to determine their associations with clinical and biochemical features of NAFLD in children.

This retrospective cross-sectional study included 398 obese children aged 11-17 years. Group 1 consisted of children with ultrasound signs of NAFLD (n=230). Group 2 included children without signs of NAFLD (n=168). Anthropometric parameters were assessed using the WHO AnthroPlus software. Body composition was evaluated using multi-frequency BIA. All children underwent abdominal ultrasound examination to detect hepatic steatosis. Biochemical blood tests were performed, including alanine aminotransferase (ALT), aspartate aminotransferase (AST), lipid profile, glucose, and insulin levels, with calculation of the HOMA-IR index. Additionally, serum concentrations of fibroblast growth factor 21 (FGF-21), cytokeratin-18 fragments (CK-18), soluble Fas ligand (FasL), and visfatin were measured by enzyme-linked immunosorbent assay to characterize metabolic disturbances and markers of apoptosis.

Children with NAFLD had significantly higher body weight, body mass index (BMI), and BMI standard deviation score (BMI SDS) compared with the control group (p<0.01). Elevated serum ALT level was detected in 23% of patients in Group 1 (53/230; 95% CI 17.9-28.9%), whereas no elevation of transaminase activity was observed in Group 2. In the NAFLD group, median level of total cholesterol, low-density lipoprotein cholesterol, and triglycerides were higher (p≤0.001), and insulin resistance was more prevalent: HOMA-IR>2.77 was observed in 73.5% (95% CI 67.4-78.8) versus 48.8% (95% CI 41.4-56.3); OR 2.91; 95% CI 1.91-4.43. According to BIA, children with NAFLD demonstrated higher fat mass (43.1 [34.7; 52.6] vs 35.6 [29.1; 43.9] kg; p<0.001) and increased indicators of visceral fat (visceral fat area and waist-to-hip ratio; p<0.001). Serum levels of CK-18 and FasL were significantly higher in children with NAFLD (p<0.01), reflecting activation of apoptotic mechanisms of hepatocyte injury.

NAFLD in obese children is associated with metabolic disturbances, including more pronounced visceral fat accumulation (according to bioimpedance analysis), dyslipidemia, and a high prevalence of insulin resistance, while elevated transaminase levels are detected only in a subset of patients. The combined use of BIA-based body composition assessment, metabolic markers of lipid and carbohydrate metabolism, and non-invasive liver instrumental evaluation may be useful for early risk assessment of NAFLD and prevention of disease progression.