Retinol binding protein-4 as a serum biomarker of intrahepatic lipid content in obese children - preliminary report

Objectives: Obesity, insulin resistance and dyslipidemia are the most significant risk factors of non-alcoholic fatty liver disease (NAFLD) but the role of adipokines in the pathogenesis of this disease is not clear. Assessment of retinol binding protein (RBP-4) seems to be promising because data from animal and human studies suggest its role in the patomechanism of insulin resistance. Therefore, the aim of the study was to evaluate the serum levels of RBP-4 in children with NAFLD. Methods: Fasting serum level of RBP-4 was determined in 42 obese children with suspected liver disease and 20 lean controls. The degree of liver steatosis was graded in ultrasound according to Saverymuttu. The intrahepatic lipid content was assessed noninvasively in a semiquantitative fashion using 1HMR spectroscopy (1.5-T scanner with PRESS sequence). Results: Fatty liver was confirmed in 30 children by ultrasonography (16 of them had also increased alanine transaminase (ALT) activity). Serum concentrations of RBP-4 were significantly higher in obese children with NAFLD compared to controls. Significant correlations were found between RBP-4 level and ultrasonographic grade of liver steatosis, intrahepatic lipid content (1HMRS) and triglycerides level, while the serum level of RBP-4 was not significantly higher in children with advanced liver steatosis (grade 2-3, n = 11) compared to patients with mild steatosis (grade 1, n = 19). The ability of RBP-4 to differentiate children with advanced liver steatosis from those with mild steatosis was not significant. Conclusion: RBP-4 can be considered as a convenient serum marker of intrahepatic lipid content in obese children.