OBJECTIVEThe incidences of nonalcoholic fatty liver disease (NAFLD) and metabolic syndrome (MS) are very high in obese children, and insulin resistance may be the key point linking them together. Debates still remain as to whether NAFLD could be a component of MS. Some researchers reported that NAFLD was a composition of MS, while the others stated that NAFLD was an independent predicting factor of MS. Here we analyzed the prevalence of NAFLD and MS in 308 obese children who came to our endocrinology department from June 2003 to September 2006, and we also evaluated the relationship between NAFLD and MS in this group of obese children.

METHODTotally 308 obese children aged from 9 to 14 years with mean age of (10.7 +/- 2.6) years were enrolled. Two hundred and thirty one were males, and 77 were females. Body mass index (BMI), waist circumference (WC), biochemical indicators, liver B-mode ultrasound examination, oral glucose tolerance test (OGTT) and insulin releasing test were performed for all of the cases. The incidences of NAFLD including simple nonalcoholic fatty liver (SNAFL) and nonalcoholic steatohepatitis (NASH) as well as MS were calculated. Three subgroups were selected according to the diagnostic criteria: Group 1: OCWLD (obese children without liver disorder), Group 2: SNAFL and Group 3: NASH. The prevalence of MS, components of MS, free insulin, whole body insulin sensitivity index (WBISI), homeostasis model of insulin resistance (HOMA(IR)) were compared among these three subgroups.

RESULT(1) Among all the obese children, the prevalence of NAFLD, SNAFL, NASH and MS was 65.9% (203), 45.5% (140), 20.5% (63) and 24.7% (76) respectively. Among all the MS children, the prevalence of NAFLD was 84.2% (64/76). The prevalence of MS was 29.3% (41/140) in SNAFL group and 36.5% (23/63) in NASH group, which was significantly higher than that of OCWLD group 11.4% (12/105) (P < 0.05), but no significant difference was found between SNAFL group and NASH group (P > 0.05). Moreover, there were significantly higher incidences in NASH group concerning every component of MS (hypertension, hyperlipidemia, hyperglycemia) compared with that of OCWLD group. The incidence of hypertension in SNAFL was significantly higher than that of OCWLD group. And the incidence of hyperlipidemia was markedly increased in NASH group compared with SNAFL group. NAFLD group had higher free insulin and more severe IR compared with that of OCWLD group. When OCWLD developed to SNAFL and NASH, free insulin and IR deteriorated calculated by HOMA-IR and WBISI. However there was no significant difference between NAFLD and MS children concerning free insulin and IR.

CONCLUSIONThe prevalence of NAFLD and MS hits high in obese children. The prevalence of NAFLD was very high among children with MS and NAFLD and MS shared the common mechanism of IR. The higher prevalence of MS and higher frequencies of MS components were tightly associated with the development of NAFLD and severity of IR.