Abstract
目的
非酒精性脂肪肝病(non-alcoholic fatty liver disease，NAFLD)是超重肥胖儿童中常见的一种代谢性疾病，其病因和发病机制尚未阐明，缺乏有效的预防和治疗手段。本研究旨在分析6~17岁超重肥胖儿童全血铜、锌、钙、镁、铁与NAFLD的关联，为超重肥胖儿童NAFLD的预防和早期干预提供依据。
方法
采用横断面研究设计，通过问卷调查收集于2019年1月至2021年12月在湖南省儿童医院就诊的超重肥胖儿童的相关资料，采集受试者凌晨空腹血并检测血糖、血脂、微量元素等指标。将超重肥胖儿童分为单纯超重肥胖组(n=400)和NAFLD组(n=202)；根据ALT水平，将NAFLD组划分为单纯性脂肪肝(non-alcoholic fatty liver，NAFL)组和非酒精性脂肪性肝炎(non-alcoholic steatohepatitis，NASH)组2个亚组。采用Logistic回归分析全血铜、锌、钙、镁、铁与NAFLD、NAFL和NASH之间的关联。
结果
共纳入602名研究对象，其中73.6%为男性，年龄为10(9，11)岁，体重指数(body mass index，BMI)为24.9(22.7，27.4) kg/m2。组间比较结果显示：NAFLD组的年龄、BMI、舒张压(diastolic blood pressure，DBP)、收缩压(systolic blood pressure，SBP)、甘油三酯(triglyceride，TG)、低密度脂蛋白(low density lipoprotein，LDL)、谷丙转氨酶(alanine transaminase，ALT)、谷草转氨酶(aspartate aminotransferase，AST)均高于单纯超重肥胖组，高密度脂蛋白(high density lipoprotein，HDL)低于单纯超重肥胖组；NAFL组的年龄、BMI、DBP、SBP、ALT、AST均高于单纯超重肥胖组，HDL低于单纯超重肥胖组；NASH组的年龄、BMI、DBP、SBP、TG、LDL、ALT、AST均高于单纯超重肥胖组，HDL低于单纯超重肥胖组(均P<0.017)。根据各微量元素水平划分为四分位组，在调整混杂因素年龄、性别、BMI、血压、TG、HDL、LDL后，与最低分位组相比，铁元素最高分位组NAFLD的OR值为1.79(95% CI 1.07~3.00)，铜、锌、钙、镁元素与NAFLD均不存在关联。NAFLD亚组分析结果显示：在调整混杂因素后，铁元素最高分位组NAFL的OR值为2.21(95% CI 1.26~3.88)，未发现铁与NASH以及铜、锌、钙、镁与NAFL或NASH之间的关联。
结论
铁水平过高增加超重肥胖儿童NAFLD(更有可能是NAFL)的患病风险，而铜、锌、钙、镁等与超重肥胖儿童NAFLD的患病风险无关。
Keywords: 超重肥胖, 儿童, 非酒精性脂肪肝病, 微量元素
Abstract
Objective
Non-alcoholic fatty liver disease (NAFLD) is a common metabolic disorder in overweight and obese children, and its etiology and pathogenesis remain unclear, lacking effective preventive and therapeutic measures. This study aims to explore the association between whole blood copper, zinc, calcium, magnesium and iron levels and NAFLD in overweight and obese children aged 6 to 17 years, providing a scientific basis for the prevention and intervention of early NAFLD in overweight and obese children.
Methods
A cross-sectional study design was used to collect relevant data from overweight and obese children who visited the Hunan Children’s Hospital from January 2019 to December 2021 through questionnaire surveys. Fasting blood samples were collected from the subjects, and various indicators such as blood glucose, blood lipid, and mineral elements were detected. All children were divided into an overweight group (n=400) and a NAFLD group (n=202). The NAFLD group was divided into 2 subgroups according to the ALT level: A non-alcoholic fatty liver (NAFL) group and a non-alcoholic steatohepatitis (NASH) group. Logistic regression analysis was used to analyze the association between minerals (copper, zinc, calcium, magnesium, and iron) and NAFLD, NAFL and NASH.
Results
A total of 602 subjects were included, of whom 73.6% were male, with a median age of 10 (9, 11) years, and a body mass index (BMI) of 24.9 (22.7, 27.4) kg/m2. The intergroup comparison results showed that compared with the overweight group, the NAFLD group had higher levels of age, BMI, diastolic blood pressure (DBP), systolic blood pressure (SBP), triglyceride (TG), low density lipoprotein (LDL), alanine transaminase (ALT) and aspartate aminotransferase (AST), and lower level of high density lipoprotein (HDL). The NAFL group had higher levels of age, BMI, DBP, SBP, ALT, and AST, and lower levels of HDL compared with the overweight group. The levels of age, BMI, DBP, SBP, TG, LDL, ALT, and AST of NASH were higher than those in the overweight group, while the level of HDL was lower than that in overweight group (all P<0.017). After adjusting for a variety of confounders, the OR of NAFLD for the highest quantile of iron was 1.79 (95% CI 1.07 to 3.00) compared to the lowest quantile, and no significant association was observed between copper, zinc, calcium, and magnesium, and NAFLD. The subgroup analysis of NAFLD showed that the OR for the highest quantile of iron in children with NAFL was 2.21 (95% CI 1.26 to 3.88), while no significant association was observed between iron level and NASH. In addition, no significant associations were observed between copper, zinc, calcium, and magnesium levels and NAFL or NASH.
Conclusion
High iron level increases the risk of NAFLD (more likely NAFL) in overweight and obese children, while copper, zinc, calcium, magnesium, and other elements are not associated with the risk of NAFLD in overweight and obese children.
Keywords: overweight and obese, children, non-alcoholic fatty liver disease, minerals
非酒精性脂肪肝病(non-alcoholic fatty liver disease，NAFLD)是指除酒精和其他明确的损肝因素外所致的肝细胞内脂肪过度沉积为主要特征的临床病理综合征，按疾病严重程度和病程进展可分为单纯性脂肪肝(non-alcoholic fatty liver，NAFL)、非酒精性脂肪性肝炎(non-alcoholic steatohepatitis，NASH)、肝纤维化和肝硬化，早期主要表现为NAFL和NASH，晚期则为肝纤维化和肝硬化[1]。NAFLD是超重肥胖儿童中一种常见的慢性病[2]，在中国超重肥胖儿童中患病率为40.4%[3]。NAFLD若不加以控制，极易发展为肝硬化、肝细胞癌等，后果十分严重。
NAFLD的病因和发病机制复杂，至今仍未阐明。国内外研究[4-8]表明，成年人血液中微量元素铜、锌、钙、镁、铁水平与NAFLD密切相关。然而，也有研究[9-11]认为血液铜、钙、铁水平与NAFLD无关。微量元素与NAFLD之间的关联尚存在争议，且这些研究多基于成年人，而在超重肥胖儿童中鲜有报道。本研究拟检测超重肥胖儿童全血铜、锌、钙、镁、铁元素水平，比较NAFLD组和单纯肥胖组之间各微量元素的差异，探讨各种微量元素与NAFLD的关联，为超重肥胖儿童NAFLD的预防与早期干预提供科学依据。
1. 对象与方法
1.1. 对象
选取2019年1月至2021年12月在湖南省儿童医院儿童保健科就诊的超重肥胖儿童为研究对象。纳入标准：1)体重指数(body mass index，BMI)符合超重肥胖标准；2)年龄6~17岁；3)同意进行微量元素检测。排除标准：1)未进行NAFLD诊断者；2)检查时已患有病毒性肝炎、肝硬化、过度饮酒引起的酒精性脂肪肝、肿瘤、药物等引起的继发性肥胖和其他重大急慢性疾病者；3)不同意合作或将其数据用作研究的受试者。所有研究对象及其监护人均签署知情同意书。本研究已获得中南大学湘雅公共卫生学院伦理委员会批准(审批号：XYGW-2018-04)。
1.2. 资料收集
1)问卷调查：由经过统一培训的调查员对研究对象及其监护人进行问卷调查，采用面对面询问的方式获取信息，避免诱导性或强制性提问。问卷内容包括被调查者的社会人口学资料(性别、年龄、个人疾病史、居住地等)、生活方式(膳食摄入、静坐时间、运动强度及时间等)、家庭情况(疾病家族史、父母健康情况)等。
2)体格测量：身高、体重通过身高体重仪测量，要求受检者脱去鞋帽，以“立正”姿势赤足站在身高仪的底板上，读取数值。身高单位为cm，精确到0.1 cm；体重单位为kg，精确到0.1 kg。计算BMI，单位为kg/m2。使用校准后的电子血压计(KF-65E型，中国可孚医疗科技)测量血压，受检者处于坐位并保持平静放松状态，每人测量2次，每次测量均记录舒张压(diastolic blood pressure，DBP)与收缩压(systolic blood pressure，SBP)，取2次测量结果的平均值作为血压值，2次测量之间的间隔为1 min，单位为mmHg(1 mmHg=0.133 kPa)。
3)实验室检查：采集受检者清晨空腹状态下的静脉血，使用全自动生化分析仪(AU5400型，日本奥林巴斯)检测谷丙转氨酶(alanine transaminase，ALT)、谷草转氨酶(aspartate aminotransferase，AST)、甘油三酯(triglyceride，TG)、总胆固醇(total cholesterol，TC)、高密度脂蛋白(high density lipoprotein，HDL)、低密度脂蛋白(low density lipoprotein，LDL)、空腹血糖(fasting blood glucose，FBG)等指标。使用AA7000原子吸收光谱仪测定全血铜、锌、钙、镁、铁水平。
4)腹部超声检查：采用彩色多普勒超声诊断仪(EPIQ 7型，荷兰飞利浦)进行腹部超声检查，受检者在清晨空腹条件下，采取仰卧位，由专业医师观察其肝脏大小、肝内光点明亮程度和分布情况。
1.3. 诊断标准
1)超重肥胖：参照《中国0~18岁儿童、青少年体块指数的生长曲线》[12]，不同年龄、性别超重肥胖BMI界值点不同，BMI超过相应年龄、性别的BMI界值点判定为超重肥胖。
2)高血压：根据《中国3~17岁儿童性别、年龄别和身高别血压参照标准》[13]，凡收缩压和/或舒张压大于或等于同年龄同性别组第95百分位数者判定为高血压。
3)NAFLD诊断标准：根据腹部超声检查结果，参照《非酒精性脂肪性肝病诊疗指南(2010年1月修订)》[14]，将符合以下标准的儿童诊断为NAFLD。无饮酒史且具备以下3项腹部超声表现中的2项：1)肝脏近场回声弥漫性增强(“明亮肝”)，回声强于肾脏；2)肝内管道结构显示不清；3)肝脏远场回声逐渐衰减。
1.4. 分组
单纯超重肥胖的儿童为单纯超重肥胖组(n=400)，确诊为NAFLD的超重肥胖儿童为NAFLD组(n=202)。根据《儿童非酒精性脂肪肝病诊断与治疗专家共识》[15]，按照ALT水平，将NAFLD组划分为NAFL组(ALT≤60 U/L，n=147)和NASH组(ALT>60 U/L， n=55)2个亚组。比较分析单纯超重肥胖组与NAFLD组及其亚组的一般资料和微量元素水平。
1.5. 统计学处理
采用Epidata软件双轨操作录入数据，对数据进行逻辑核查后建立数据库。使用SPSS 26.0对数据进行统计分析。计数资料以例数和构成比表示，组间比较采用χ2检验；计量资料经正态性检验，均不服从正态分布，以中位数(第1四分位数，第3四分位数)表示，组间比较采用Wilcoxon秩和检验。组间比较采用Bonferroni法矫正检验水准，矫正后α=0.017， P<0.017判定为差异有统计学意义。根据各微量元素水平分为Q1~Q4四分位组，采用Logistic回归模型分别分析微量元素与NAFLD、NAFL及NASH的关联。
2. 结 果
2.1. 单纯超重肥胖儿童与NAFLD儿童基本资料比较
共纳入602名研究对象，其中73.6%为男性，年龄为10(9，11)岁，BMI为24.9(22.7，27.4) kg/m2。NAFLD组、NAFL组与NASH组的男性比例均高于单纯超重肥胖组(均P<0.017)。NAFLD组的年龄、BMI、DBP、SBP、TG、LDL、ALT、AST均高于单纯超重肥胖组，HDL低于单纯超重肥胖组，差异均有统计学意义(均P<0.017)。NAFL组年龄、BMI、DBP、SBP、ALT、AST均高于单纯超重肥胖组，HDL低于单纯超重肥胖组，差异均有统计学意义(均P<0.017)。NAFL组与单纯超重肥胖组间TG和LDL的差异均无统计学意义(均P>0.017)。NASH组年龄、BMI、DBP、SBP、TG、LDL、ALT、AST均高于单纯超重肥胖组，HDL低于单纯超重肥胖组，差异均有统计学意义(均P<0.017)。此外，NAFLD组、NAFL组、NASH组血糖、TC以及食用蔬菜水果频次、喝含糖饮料频次、中高等体力活动频次和静坐时间等与单纯超重肥胖组的差异均无统计学意义(均P>0.017，表1)。
表1.
单纯超重肥胖儿童与NAFLD儿童基本资料比较
Table 1 Comparison of characteristics between overweight and obese children and NAFLD children
| 组别 | n | 性别/[例(%)] | 年龄/岁 | BMI/(kg·m-2) | DBP/mmHg | SBP/mmHg | |
|---|---|---|---|---|---|---|---|
| 男 | 女 | ||||||
| 单纯超重肥胖 | 400 | 274(68.5) | 126(31.5) | 10(8, 11) | 23.99(22.06, 26.36) | 66(60, 73) | 114(105, 123) |
| NAFL | 147 | 120(81.6)* | 27(18.4)* | 10(9, 12)* | 26.41(24.07, 28.71)* | 68(64, 76)* | 120(113, 127)* |
| NASH | 55 | 49(89.1)* | 6(10.9)* | 11(10, 12)* | 26.65(24.46, 29.97)* | 71(65, 77)* | 120(110, 133)* |
| NAFLD | 202 | 169(83.7)* | 33(16.3)* | 11(9, 12)* | 26.41(24.27, 29.07)* | 69(64, 77)* | 120(113, 129)* |
| 组别 | 血糖/(mmol·L-1) | TG/(mmol·L-1) | TC/(mmol·L-1) | HDL/(mmol·L-1) | LDL/(mmol·L-1) | ALT/(U·L-1) |
|---|---|---|---|---|---|---|
| 单纯超重肥胖 | 4.51(4.25, 4.80) | 1.06(0.77, 1.43) | 3.90(3.49, 4.34) | 1.23(1.09, 1.39) | 2.13(1.82, 2.51) | 19.30(14.90, 27.00) |
| NAFL | 4.49(4.17, 4.89) | 1.15(0.80, 1.66) | 3.98(3.52, 4.52) | 1.16(1.01, 1.31)* | 2.30(1.88, 2.64) | 29.80(18.40, 42.10)* |
| NASH | 4.56(4.28, 4.69) | 1.35(0.94, 1.94)* | 4.11(3.54, 4.60) | 1.10(0.99, 1.23)* | 2.44(1.92, 2.89)* | 96.50(77.90, 113.20)* |
| NAFLD | 4.50(4.19, 4.83) | 1.18(0.86, 1.71)* | 4.01(3.52, 4.54) | 1.15(1.00, 1.30)* | 2.33(1.90, 2.67)* | 38.80(22.05, 68.18)* |
| 组别 | AST/(U·L-1) | 食用蔬菜水果频次/[例(%)] | 喝含糖饮料频次/[例(%)] | ||||||
|---|---|---|---|---|---|---|---|---|---|
|
基本 不吃 |
每周 1~3次 |
每周 4~6次 |
每天 都吃 |
不喝 | 很少 | 有时 | 总是 | ||
| 单纯超重肥胖 | 22.40(19.20, 26.30) | 15(3.8) | 60(15.0) | 46(11.5) | 278(69.7) | 80(20.1) | 192(48.1) | 109(27.3) | 18(4.5) |
| NAFL | 25.40(22.40, 29.80)* | 7(4.8) | 20(13.6) | 12(8.1) | 108(73.5) | 30(20.4) | 61(41.5) | 45(30.6) | 11(7.5) |
| NASH | 48.30(39.00, 60.40)* | 1(1.8) | 8(14.6) | 12(21.8) | 34(61.8) | 7(12.7) | 21(38.2) | 22(40.0) | 5(9.1) |
| NAFLD | 28.20(23.38, 37.85)* | 8(4.0) | 28(13.8) | 24(11.9) | 142(70.3) | 37(18.3) | 82(40.6) | 67(33.2) | 16(7.9) |
| 组别 | 中高等体力活动频次/[例(%)] | 平均每天静坐时间/[例(%)] | |||||
|---|---|---|---|---|---|---|---|
| 没有 | 每周3次以内 | 每周4~6次 | 每天 | <6 h | 6~9 h | >9 h | |
| 单纯超重肥胖 | 75(18.9) | 90(22.7) | 74(18.6) | 158(39.8) | 54(13.6) | 262(66.0) | 81(20.4) |
| NAFL | 29(19.7) | 27(18.4) | 20(13.6) | 71(48.3) | 21(14.3) | 92(62.6) | 34(23.1) |
| NASH | 12(21.8) | 10(18.2) | 15(27.3) | 18(32.7) | 6(10.9) | 35(63.6) | 14(25.5) |
| NAFLD | 41(20.3) | 37(18.3) | 35(17.3) | 89(44.1) | 27(13.3) | 127(62.9) | 48(23.8) |
计量资料以中位数(第1四分位数，第3四分位数)表示。与单纯超重肥胖组相比，*P<0.017。1 mmHg=0.133 kPa。NAFL：单纯性脂肪肝；NASH：非酒精性脂肪性肝炎；NAFLD：非酒精性脂肪肝病；BMI：体重指数；DBP：舒张压；SBP：收缩压；TG：甘油三酯；TC：总胆固醇；HDL：高密度脂蛋白；LDL：低密度脂蛋白；ALT：谷丙转氨酶；AST：谷草转氨酶。
2.2. 单纯超重肥胖儿童与NAFLD儿童微量元素水平
单纯超重肥胖儿童与NAFLD儿童微量元素水平的Wilcoxon秩和检验分析结果显示：NAFLD组铁元素水平高于单纯超重肥胖组，差异具有统计学意义 (P<0.017)，而铜、锌、钙、镁差异均无统计学意义(均P>0.017，表2)。NAFLD亚组分析结果显示：NAFL组镁和铁元素水平均高于单纯超重肥胖组(均 P<0.017)，而NASH组与单纯超重肥胖组5种元素差异均无统计学意义(均P>0.017，表2)。
表2.
单纯超重肥胖儿童与NAFLD儿童全血微量元素水平
Table 2 Whole-blood minerals levels of overweight and obese children and NAFLD children
| 组别 | 铜/(mg·L-1) | 锌/(mg·L-1) | 钙/(mg·L-1) | 镁/(mg·L-1) | 铁/(mg·L-1) |
|---|---|---|---|---|---|
| 单纯超重肥胖 | 0.94(0.84, 1.02) | 6.61(5.81, 7.54) | 63.20(58.51, 66.82) | 37.25(34.60, 40.05) | 413.37(378.82, 445.45) |
| NAFL | 0.95(0.85, 1.01) | 6.77(5.83, 7.66) | 62.43(57.73, 66.74) | 38.43(35.81, 40.64)* | 428.67(388.01, 462.45)* |
| NASH | 0.91(0.83, 1.01) | 6.55(6.12, 7.18) | 62.02(58.43, 66.47) | 37.74(34.34, 39.34) | 413.37(378.26, 448.78) |
| NAFLD | 0.95(0.85, 1.01) | 6.69(5.93, 7.55) | 62.25(58.08, 66.54) | 38.08(35.62, 40.25) | 426.00(382.80, 458.12)* |
计量资料以中位数(第1四分位数，第3四分位数)表示。与单纯超重肥胖组相比，*P<0.017。NAFL：单纯性脂肪肝；NASH：非酒精性脂肪性肝炎；NAFLD：非酒精性脂肪肝病。
2.3. 微量元素与NAFLD的关联分析
筛选表1中组间差异具有统计学意义的变量，并对TG、TC、HDL、LDL等指标进行相关分析，去除相关性较强的协变量。最终将年龄、性别、BMI、血压、TG、HDL、LDL作为混杂因素纳入Logistic回归模型。调整上述混杂因素后，结果显示铁与NAFLD的患病风险有关，与最低分位Q1组相比，最高分位Q4组NAFLD的OR值为1.79(95% CI 1.07~3.00)；而铜、锌、钙、镁与NAFLD的患病风险均无关(P trend>0.05)。
NAFLD亚组分析结果显示：在调整多种混杂因素后，对于NAFL组，铁与NAFL的患病风险有关，与最低分位Q1组相比，铁元素最高分位Q4组NAFL的OR值为2.21(95% CI 1.26~3.88)；而铜、锌、钙、镁与NAFL均无关(P trend>0.05)。对于NASH组，铜、锌、钙、镁、铁与NASH的患病风险均无关(P trend>0.05，表3和表4)。
表3.
铜、锌、钙元素水平与NAFLD的关联
Table 3 Association between copper, zinc, and calcium levels and NAFLD
| 铜 | OR | 95% CI | P | 锌 | OR | 95% CI | P | 钙 | OR | 95% CI | P |
|---|---|---|---|---|---|---|---|---|---|---|---|
| NAFLD | NAFLD | NAFLD | |||||||||
| Q1 | ref | Q1 | ref | Q1 | ref | ||||||
| Q2 | 1.03 | 0.61~1.75 | 0.90 | Q2 | 0.99 | 0.58~1.69 | 0.98 | Q2 | 0.97 | 0.59~1.61 | 0.91 |
| Q3 | 1.45 | 0.85~2.47 | 0.18 | Q3 | 1.20 | 0.71~2.01 | 0.50 | Q3 | 0.75 | 0.44~1.27 | 0.28 |
| Q4 | 1.04 | 0.61~1.79 | 0.88 | Q4 | 1.00 | 0.59~1.69 | 0.99 | Q4 | 0.85 | 0.50~1.46 | 0.56 |
| P trend | 0.48 | P trend | 0.87 | P trend | 0.69 | ||||||
| NAFL | NAFL | NAFL | |||||||||
| Q1 | ref | Q1 | ref | Q1 | ref | ||||||
| Q2 | 0.96 | 0.53~1.73 | 0.89 | Q2 | 0.74 | 0.40~1.35 | 0.32 | Q2 | 0.89 | 0.51~1.56 | 0.69 |
| Q3 | 1.70 | 0.97~3.09 | 0.06 | Q3 | 1.05 | 0.60~1.84 | 0.88 | Q3 | 0.76 | 0.43~1.34 | 0.34 |
| Q4 | 1.14 | 0.63~2.07 | 0.66 | Q4 | 1.06 | 0.61~1.86 | 0.83 | Q4 | 0.88 | 0.49~1.57 | 0.65 |
| P trend | 0.15 | P trend | 0.61 | P trend | 0.82 | ||||||
| NASH | NASH | NASH | |||||||||
| Q1 | ref | Q1 | ref | Q1 | ref | ||||||
| Q2 | 1.25 | 0.55~2.86 | 0.60 | Q2 | 1.88 | 0.78~4.52 | 0.16 | Q2 | 1.05 | 0.47~2.35 | 0.91 |
| Q3 | 0.81 | 0.32~2.09 | 0.67 | Q3 | 1.77 | 0.72~4.34 | 0.22 | Q3 | 0.75 | 0.31~1.83 | 0.53 |
| Q4 | 0.82 | 0.34~1.99 | 0.66 | Q4 | 0.67 | 0.24~1.88 | 0.44 | Q4 | 0.71 | 0.28~1.80 | 0.47 |
| P trend | 0.72 | P trend | 0.10 | P trend | 0.78 |
NAFL：单纯性脂肪肝；NASH：非酒精性脂肪性肝炎；NAFLD：非酒精性脂肪肝病。在铜元素中，Q1：<0.84 mg/L；Q2：0.84~<0.94 mg/L；Q3：0.94~<1.01 mg/L；Q4：≥1.01 mg/L。在锌元素中，Q1：<5.87 mg/L；Q2：5.87~<6.64 mg/L；Q3：6.64~<7.55 mg/L；Q4：≥7.55 mg/L。在钙元素中，Q1：<58.50 mg/L；Q2：58.50~<63.11 mg/L；Q3：63.11~<66.98 mg/L；Q4：≥66.98 mg/L。
表4.
镁、铁元素水平与NAFLD的关联
Table 4 Association between magnesium and iron levels and NAFLD
| 镁 | OR | 95% CI | P | 铁 | OR | 95% CI | P |
|---|---|---|---|---|---|---|---|
| NAFLD | NAFLD | ||||||
| Q1 | ref | Q1 | ref | ||||
| Q2 | 1.30 | 0.76~2.22 | 0.34 | Q2 | 0.98 | 0.58~1.68 | 0.95 |
| Q3 | 1.37 | 0.81~2.31 | 0.25 | Q3 | 0.97 | 0.57~1.66 | 0.92 |
| Q4 | 1.24 | 0.72~2.12 | 0.44 | Q4 | 1.79 | 1.07~3.00 | 0.03 |
| P trend | 0.68 | P trend | 0.05 | ||||
| NAFL | NAFL | ||||||
| Q1 | ref | Q1 | ref | ||||
| Q2 | 1.41 | 0.78~2.56 | 0.26 | Q2 | 1.08 | 0.59~1.96 | 0.81 |
| Q3 | 1.31 | 0.72~2.38 | 0.38 | Q3 | 0.97 | 0.52~1.79 | 0.92 |
| Q4 | 1.60 | 0.89~2.88 | 0.12 | Q4 | 2.21 | 1.26~3.88 | 0.01 |
| P trend | 0.47 | P trend | 0.01 | ||||
| NASH | NASH | ||||||
| Q1 | ref | Q1 | ref | ||||
| Q2 | 0.91 | 0.38~2.21 | 0.84 | Q2 | 0.83 | 0.34~2.01 | 0.68 |
| Q3 | 1.34 | 0.60~2.98 | 0.47 | Q3 | 0.99 | 0.45~2.26 | 0.99 |
| Q4 | 0.40 | 0.14~1.10 | 0.08 | Q4 | 0.88 | 0.36~2.13 | 0.77 |
| P trend | 0.11 | P trend | 0.97 |
NAFL：单纯性脂肪肝；NASH：非酒精性脂肪性肝炎；NAFLD：非酒精性脂肪肝病。在镁元素中，Q1：<34.76 mg/L；Q2：34.76~<37.59 mg/L；Q3：37.59~<40.07 mg/L；Q4：≥40.07 mg/L。在铁元素中，Q1：<381.68 mg/L；Q2：381.68~<418.47 mg/L；Q3：418.47~<451.01 mg/L；Q4：≥451.01 mg/L。
3. 讨 论
本研究探讨了6~17岁超重肥胖儿童全血铜、锌、钙、镁、铁5种微量元素与NAFLD之间的关联，结果显示：在调整多种混杂因素后，铁水平过高增加NAFLD的患病风险，而铜、锌、钙、镁与NAFLD的患病风险无关。NAFLD亚组分析结果显示：在调整多种混杂因素后，铁水平过高增加NAFL的患病风险，而铜、锌、钙、镁与NAFL的患病风险无关。此外，铜、锌、钙、镁、铁均与超重肥胖儿童NASH无关。
本研究结果与国内外多项研究结果类似。蔡海芳等[16]研究表明，肥胖儿童与肥胖NAFLD儿童血清铁蛋白水平高于正常对照组儿童。许盼等[17]发现，NAFLD患者存在血清铁蛋白水平升高，且血清铁蛋白与NAFLD病情严重程度相关。Demircioğlu等[18]发现，肥胖伴NAFLD儿童体内转铁蛋白饱和度高于单纯肥胖儿童，提示NAFLD儿童体内铁储存水平的升高。
研究[19]表明：铁水平过高导致NAFLD发生、发展的机制可能与胰岛素抵抗和氧化应激有关，当机体组织内铁水平过高时，会刺激白细胞介素-6和肿瘤坏死因子-α分泌增加，从而抑制脂联素的表达，影响胰岛素受体的功能。同时，过量铁沉积在胰岛β细胞中会直接损伤胰岛细胞，使其大量凋亡，影响胰岛素的分泌[20]。胰岛素抵抗是NAFLD发生、发展中的重要环节，因此，铁可通过胰岛素抵抗诱导NAFLD的发生。此外，铁是机体内最重要的氧化反应促进剂[21]，过量铁通过Fenton反应产生活性氧，诱导脂质氧化应激反应并形成过氧化产物，当过氧化产物超过机体抗氧化系统清除能力时，会损伤肝组织，使肝细胞死亡。而肝细胞死亡又会影响铁稳态，进一步诱导铁超载，加重肝损伤和肝纤维化[22]。本研究结果提示铁过量会增加NAFLD的患病风险，因此，在超重肥胖儿童NAFLD的预防中，要注意铁摄入过量带来的风险。然而，也有部分研究[23-24]认为血清铁水平与NAFLD发生风险无关，这可能是由于不同的研究采用的铁代谢指标不同所致。
本研究未发现铁与NASH的相关性。关于铁在NASH发生、发展中的作用，有学者[25]发现，许多NASH患者存在稳态铁调节因子——HFE基因突变，而HFE基因突变是铁超载的主要原因，Aigner等[26]和Bonkovsky等[27]在成年人的研究中证实了这一点。然而，也有研究[28]发现NASH患者的铁水平均在正常范围内，甚至低于正常对照组[29]，这可能是由于NASH患者本身的肥胖导致全身暴露于炎症细胞因子，诱导肝细胞和脂肪组织中铁调素的过度表达，从而减少铁的吸收[30]，也可能与铁超载的迟发性有关。总之，铁在NASH发病机制中的作用尚不清楚，还需进一步研究铁与NASH的关系。
关于铜、锌、钙、镁与NAFLD的关联，相关研究结论并不一致，部分研究[10, 31-32]认为低水平铜、锌、钙、镁与NAFLD的患病风险有关，可能与铜、锌、镁等是构成超氧化物歧化酶、过氧化氢酶等多种抗氧化酶的重要元素有关[33]，铜、锌水平过低会影响这些酶的活性，削弱抗氧化防御系统，导致活性氧水平升高和脂质相关氧化损伤。也有研究认为铜[11]、锌[23]、钙[9]与NAFLD的患病风险无关，此外，关于血镁与超重肥胖儿童NAFLD的关联研究较少，本研究也未发现铜、锌、钙、镁与NAFLD患病风险存在关联，因此，未来仍需更多的研究探讨矿物质与NAFLD的关联。
目前，国内外关于超重肥胖儿童NAFLD与血液微量元素的大样本关联研究较少，本研究通过较大样本探讨了5种微量元素铜、锌、钙、镁、铁与超重肥胖儿童NAFLD的关联，并控制了可能的混杂因素，使结果更为可靠，但也存在一定的局限性。第一，本研究采取的是横断面的研究设计，无法确定铁水平升高与超重肥胖儿童NAFLD发生的先后顺序，不能做出因果推断。第二，本研究纳入的NASH组儿童样本量较小，还需进一步扩大样本量进行验证。
综上所述，本研究发现铁元素与NAFLD的患病风险有关，在医院保健工作中，不仅要关注儿童矿物质的缺乏，也要注意避免微量元素摄入过多带来的危害，并加强对儿童NAFLD的预防，提出针对性的干预措施，控制和避免疾病进一步的发展。
基金资助
国家自然科学基金(81872641)；湖南省自然科学基金(2021JJ30901)。This work was supported by the National Natural Science Foundation (81872641) and the Natural Science Foundation of Hunan Province (2021JJ30901), China.
利益冲突声明
作者声称无任何利益冲突。
作者贡献
黄智航 统计分析，论文撰写与修改；罗米扬、钟燕、罗家有 论文指导，基金资助；戴文、姚珍珍、欧阳思思、徐宁安、周海湘、李雄伟 数据收集、录入和整理，对论文内容进行批评性审阅。所有作者阅读并同意最终的文本。
Footnotes
http://dx.chinadoi.cn/10.11817/j.issn.1672-7347.2024.230274
原文网址
http://xbyxb.csu.edu.cn/xbwk/fileup/PDF/202403426.pdf
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