Abdominal fat index — a non-invasive marker of hepatic steatosis and insulin resistance in children

• Main Authors: N.Yu. Zavhorodnia, O.Yu. Lukyanenko, I.S. Konenko, O.P. Petishko, V.E. Kudryavtseva
• Format: Article
• Language: English
• Published: Publishing House Zaslavsky 2017-04-01
• Series: Zdorovʹe Rebenka
• Subjects: obesity; fat index; hepatic steatosis; insulin resistance; children
• Online Access: http://childshealth.zaslavsky.com.ua/article/view/104226
• ISSN: 2224-0551; 2307-1168

Background. Elevation of visceral fat (VF) thickness is considered as a risk factor for non-alcoholic fatty liver disease in children. Non-invasive methods for evaluating the type of fat distribution allow to obtain useful markers for stratifying the risk of liver steatosis in children, dynamic monitoring and evaluation of therapy effectiveness. Aim of our study was to investigate anthropometric and sonographic parameters of the adipose tissue distribution and to determine the possibility of their usage as diagnostic markers of hepatic steatosis in children; to explore their relationship with carbohydrate metabolism. Materials and methods. The study involved 56 patients aged 5 to 17 years. Diagnostics of hepatic steatosis was conducted using FibroScan® 502 Touch with determination of controlled attenuation parameter. The distribution of adipose tissue was evaluated on the basis of measuring the thickness of subcutaneous (SF), preperitoneal fat (PPF) and calculating abdominal fat index (AFI): AFI = SFmax/PPFhmin. Also, we measured the thickness of visceral fat (the distance between linea alba and the front wall of the aorta). The insulin level was determined using enzyme-linked immunosorbent assay that followed by calculation of the homeostasis model assessment index (HOMA). According to the presence of steatosis and body mass index, patients were divided into 3 groups: group 1 — 33 children with liver steatosis and overweight or obesity, group 2 — 18 persons with overweight or obesity without liver steatosis, group 3 (control) — 5 patients with normal weight without liver steatosis. Results. Obesity was diagnosed in 87.9 % of children in group 1 and 65 % — in group 2. We found that formation of steatosis was accompanied by an increase in preperitoneal fat thickness, in group 1 it was 1.4 times higher than in group 2 and 2 times — in group 3. The thickness of subcutaneous fat in children in group 1 was 1.18 times higher than in group 2 and 2.1 times higher than in group 3. Average value of visceral fat thickness was the highest among patients of group 1 and differed significantly from that of in children of group 3 (p < 0.05), but the significance of differences between groups 1 and 2 was not sufficient (p = 0.1). AFI was significantly higher in persons with hepatic steatosis, as compared to children with normal weight and obese children (0.49 ± 0.24 — in group 1, 0.30 ± 0.10 — in group 2 and 0.24 ± 0.08 — in group 3; p < 0.05). The level of HOMA index in children of group 1 was 1.7 times higher than that of in group 2 (p < 0.05). Providing correlation analysis, we revealed that AFI had a positive correlation with the level of HOMA index (r = 0.540. p < 0.05) and a positive correlation with C-peptide levels (r = 0.99, p < 0.05). C-peptide level was associated with growth of the VF/SF ratio (r = 0.78, p < 0.05) and showed a negative correlation with the thickness of subcutaneous fat (r = 0.42, p < 0.05). Conclusion. Our study showed that abdominal fat index characterizes the distribution of adipose tissue in children and can be used as a non-invasive marker of steatohepatosis and insulin resistance. It was determined that AFI level above 0.35 with sensitivity of 88.9 % indicates the presence of hepatic steatosis in children.