[Quantitative assessment of intrahepatic fat content in children and adolescents with non-alcoholic fatty liver disease].

OBJECTIVE: To quantitatively evaluate clinical significance of intrahepatic fat (IHF) content in children and adolescents with non-alcoholic fatty liver disease (NAFLD).

METHODS: Ninety-three obese children were enrolled in this study. Physical parameters, liver function, serum lipids, glycemic and insulin related parameters were measured. Liver B-mode ultrasound (US) examination was performed. IHF content was quantified by 1H magnetic resonance spectroscopy (1H MRS). Three subgroups were classified according to the conditional diagnostic criteria for obese children: simple obesity (n=31), NAFLD-1 (US fatty liver and normal alanine aminotransterase, n=33) and NAFLD-2 (US fatty liver and elevated alanine aminotransterase, n=29). Twenty healthy age- and sex-matched children served as a control group. IHF content among the four groups was compared. The relationship of IHF content with other common clinical laboratory parameters and independent factors influencing increased IHF content were investigated.

RESULTS: IHF content measured by 1H MRS was 0.80% (0.4%-1.0%), 2.9% (1.7%-4.30%), 14.0% (7.2%-17.5%) and 18.8% (14.0%-29.1%) respectively in the control, simple obese, NAFLD-1 and NAFLD-2 groups. There were significant differences in IHF content between the groups. Univariate correlation analysis demonstrated that IHF content was positively correlated with waist circumference, hip circumference, waisttohip ratio, body mass index, systolic blood pressure, diastolic blood pressure, alanine aminotransferase, aspartate aminoreansferase, γ-glutamic acid transtetase, triglyceride, low-density lipoprotein, OGTT 2-hour plasma glucose, fasting insulin, 2-hour insulin and insulin resisfence, and negatively correlated with high-density lipoprotein. Multivariate linear regression analysis demonstrated three independent risk factors for increased IHF content: increased waist circumference, increased 2-hour plasma glucose and decreased high-density lipoprotein levels.

CONCLUSIONS: IHF content determined by 1H MRS can reflect early hepatic fatty infiltration and is closely related to the occurrence and progress of NAFLD in obese children and adolescents. There is a significant correlation between most of common clinical laboratory parameters and IHF content, and waist circumference, high-density lipoprotein and OGTT 2-hour plasma glucose are independent factors impacting IHF content.