学龄儿童肥胖相关性脂肪肝及脂代谢紊乱的病例对照研究

目的 研究学龄儿童肥胖与非乙醇性脂肪肝病（nonalcoholic fatty liver disease, NAFLD）及脂肪代谢紊乱等相关因素的关系。方法 采用典型整群抽样方法选取北京市海淀区中等水平的4所小学和4所中学，在知情同意的前提下，从中抽取659名7～18岁肥胖儿童作为肥胖组，603名正常体重儿童作为对照组，进行问卷、身体测量、腹部B超脂肪肝检查及血清总胆固醇（TC）、三酰甘油（TG）、高密度脂蛋白胆固醇（HDL-C）和低密度脂蛋白胆固醇（LDL-C）水平，血清丙氨酸转氨酶（ALT）和天冬氨酸转氨酶（AST）等生化指标检测。超重、肥胖采用中国学龄儿童超重、肥胖BMI筛查标准进行评价；血脂异常的判定标准：静脉血清TC≥5.20 mmol·L-1，TG≥1.70 mmol·L-1，HDL-C≤1.03 mmol·L-1，LDL C≥3.12 mmol·L-1；肝功能异常：静脉血清ALT≥40.0 U·L-1和（或）AST≥45.0 U·L-1；NAFLD诊断依据2003年中华医学会肝脏病学分会脂肪肝和酒精性肝病学组公布的非酒精性脂肪性肝病诊断标准进行。统计方法包括计量资料的描述统计、协方差分析、卡方检验、二分类多因素Logistic回归分析及趋势卡方检验等。结果 肥胖组有3例未行脂肪肝B超检测，肥胖组B超脂肪肝和NAFLD的检出率分别为28.0%（184/656）和10.2%（67/656），对照组脂肪肝和NAFLD的检出率分别为0.3%（2/603）和0.2%（1/603），差异有统计学意义（P<0.01），肥胖组TG、TC、LDL-C水平明显高于对照组，HDL-C水平明显低于对照组（P<0.01）。肥胖同时罹患NAFLD时，血脂异常进一步加重，ALT及AST异常也更明显，以ALT升高为著；随着肥胖的加重，脂肪代谢紊乱及肝功能损害程度逐渐上升。结论 肥胖儿童伴发NAFLD较为普遍，单纯性肥胖对儿童的肝功能和脂肪代谢等均造成危害，并随肥胖程度逐渐加重，对中度以上肥胖儿童建议常规进行腹部B超检查。

A case-control study on nonalcoholic fatty liver disease and dyslipidmias in obese schoolchildren

Objective To investigate the relationship between obesity and lipids disturbance and Nonalcoholic Fatty Liver Disease （NAFLD）in schoolchildren.Methods This was a case control study. 4 elementary schools and 4 middle schools were selected from Haidian district in Beijing with representative cluster sampling.659 obese children and 603 normal weight children aged 7 to 18 years were recruited from the 8 schools with uncompletely randomized sampling as the case and control groups. Data of anthropometric measurements including weight and height were collected from March to May, 2007. Body Mass Index （BMI）was calculated by weight（in kilograms）/height2（in meters）. Obsity and normal weight were determined according to the sex-, age-specific body mass index (BMI) cutoffs, recommended by the Working Group on Obesity in China. Liver was tested by ultrasonography (Toshiba SA 340A), and abnormal hepatic sonograms were diagnosed. Elevated glutamate pyruvate transaminase was diagnosed by ALT≥40.0 U·L-1 and elevated glutamic oxalacetic transaminase was determined by AST≥45.0 U·L-1. Nonalcoholic fatty liver was diagnosed according to the diagnostic criteria of nonalcoholic fatty liver disease recommended by the Fatty Liver and Alcoholic Liver Disease Study Group of Chinese Liver Disease Association.Serum levels of TG≥1.70 mmol·L-1, TC≥5.20 mmol·L-1, HDL C≤1.03 mmol·L-1 and LDL C≥3.12 mmol·L-1 were defined as raised TG, raised TC, Low HDL C and elevated LDL C, respectively. TG was skewed distribution and natural logarithmical transformations were performed. Analysis of covariance adjusted for gender and age, Chi square test and binary logistic regression analysis were conducted to analyze the relationship between obesity and lipid profiles, fatty liver and NAFLD in different groups. Chi-square test for trend was used to analyze the changes of lipid profiles and NAFLD with obesity aggravated.Results Hepatic sonograms test demonstrated that 186 students had fatty liver and 68 children were diagnosed as NAFLD. The prevalence of fatty liver tested by Ultrasonography was 28.0%(184/656) and that of NAFLD was 10.2%(67/656) in obese children, while those were 0.3%(2/603) and 0.2%(1/603) in normal weight group, respectively. The levels of TG, TC, LDL C, HDL-C were 1.16(0.87-1.52) mmol·L-1, （4.24±0.03） mmol·L-1,（1.30±0.01） mmol·L-1 and （2.46±0.02） mmol·L-1 in obese group were significantly higher than those ［TG 0.85(0.65-1.07) mmol·L-1, TC（4.08±0.03） mmol·L-1, LDL-C（1.59±0.01） mmol·L-1 and HDL-C（2.04±0.02） mmol·L-1 ］in normal weight group (P<0.01). The prevalence rates of HTG ［17.3%(114/659)］, HTC［9.6%（63/659）］, HLDL-C［13.2%（7/659）］, LHDL-C［19.3%（27/659）］, elevated ALT/AST［14.7%（97/659）］/［3.6%（24/659）］, fatty liver［28.0%（184/659）］and NAFLD［10.2%（67/659］ were significantly higher in obese group than those［HTG 3.6%（2/603）、HTC 4.8%（29/603）、LHDL-C 5.1%（31/603）、HLDL-C 2.0%（12/603）、elevatedALT/AST 0.8%（5/603）/0.8%（5/603）、fatty liver 0.3%(2/603)、NAFLD 0.2%（1/603）］ in normal weight group. The levels of lipids profiles of TG［1.40(0.93-2.08)mmol·L-1］, TC（4.44±0.09） mmol·L-1, HDL-C（1.23±0.03） mmol·L-1 and LDL-C（2.70±0.07）mmol·L-1 in obese children with NAFLD were higher than those［TG 1.13(0.85-1.49) mmol·L-1, TC（4.22±0.03） mmol·L-1, HDL-C（1.31±0.01）mmo·L-1 and LDL-C（2.43±0.02）mmol·L-1in obese children without NAFLD. The dyslipidmias in obese children with NAFLD was more serious comparing with that in obese children without NAFLD (P<0.001)，the changes of HTG was especially significant. Further more dyslipidmias, liver function disturbance, fatty liver tested by hepatic sonograms and NAFLD were aggravated with the increase of obesity by. Chi-square test for trend except HTG.Conclusions Dyslipidmias, liver function disturbance, fatty liver and NAFLD were more serious in obese schoolchildren than in those with normal weight. The dyslipidmias and fatty liver were aggravated with the increase of obesity. Ultrasonographic test of liver should be done in midrange for significant obese schoolchildren.