全血锌水平在儿童和青少年自主神经介导性晕厥中的临床意义

Clinical value of whole blood zinc in children and adolescents with neurally-mediated syncope

目的探讨锌水平在儿童和青少年自主神经介导性晕厥(NMS)中的临床价值。方法选取行直立倾斜试验(HUTT)并检测微量元素和维生素(Vit)的NMS患儿102例(NMS组),根据HUTT结果分为HUTT阳性组(83例)和HUTT阴性组(19例)。HUTT阳性组中血管迷走性晕厥(VVS)32例、体位性心动过速综合征(POTS)53例(有2例患儿同时合并VVS)。以检测微量元素的健康体检儿童100名作为正常对照A组,检测Vit的健康体检儿童100名作为正常对照B组。检测所有研究对象全血锌、钙、铜、镁、铁水平和血清Vit A、Vit B1、Vit B2、Vit B6、Vit B9、Vit C、Vit D、Vit E水平。采用二元Logistic回归分析评估发生NMS的危险因素。采用受试者工作特征(ROC)曲线评估各项指标诊断NMS或鉴别诊断VVS与POTS的效能。结果NMS组全血锌、钙、铁水平与正常对照A组比较,差异均有统计学意义(P<0.05);其他指标NMS组与2个正常对照组之间差异均无统计学意义(P>0.05)。HUTT阳性组全血锌、钙、铁水平均低于正常对照A组(P<0.05)。HUTT阴性组各项微量元素与HUTT阳性组和正常对照A组比较,差异均无统计学意义(P>0.05)。VVS组全血锌水平低于正常对照A组(P<0.05)。POTS组全血锌、钙、镁、铁水平均低于正常对照A组(P<0.05)。VVS组全血镁水平高于POTS组(P<0.05)。二元Logistic回归分析结果显示,锌水平下降是NMS发生的危险因素[比值比(odds ratio,OR)=0.726,95%可信区间(CI)为0.652~0.807],全血钙、铁水平降低与NMS发生无关(OR值分别为1.772、0.472,95%CI分别为0.639~4.909、0.090~2.476)。ROC曲线分析结果显示,全血锌水平诊断NMS的曲线下面积(AUC)为0.800,最佳临界值为80.09μmol/L,敏感性为74.5%,特异性为80.0%。全血镁水平鉴别诊断VVS和POTS的AUC为0.631,最佳临界值为1.33 mmol/L,敏感性为67.9%,特异性为59.4%。结论锌缺乏可能与儿童和青少年NMS的发生有关。镁对VVS与POTS的鉴别可能有一定的参考价值。

Objective To investigate the clinical value of whole blood zinc in children and adolescents with neurally-mediated syncope(NMS).Methods Totally,102 NMS children(NMS group)who underwent head-up tilt test(HUTT)and tested trace elements and vitamins(Vit)were enrolled.According to the results of HUTT,83 cases were classified into HUTT positive group,and 19 cases were classified into HUTT negative group.The HUTT positive group included 32 cases of vasovagal syncope(VVS)and 53 cases of postural orthostatic tachycardia syndrome(POTS).Two patients were diagnosed with both VVS and POTS.A total of 100 healthy age-matched children who tested trace elements and 100 healthy age-matched children who tested Vit were enrolled as control group A and control group B,respectively.The levels of zinc,calcium,copper,magnesium and iron in whole blood and the levels of Vit A,Vit B1,Vit B2,Vit B6,Vit B9,Vit C,Vit D and Vit E in serum were determined.Binary Logistic regression analysis was used to assess risk factors of NMS.Receiver operating characteristic(ROC)curve was used to evaluate the predictive value in diagnosing NMS and the predictive value in differentiating VVS and POTS.Results Compared with control group A,the differences of zinc,calcium and iron had statistical significance in NMS group(P<0.05).There was no statistical significance in the other items between NMS group and control groups(P>0.05).The levels of zinc,calcium and iron in HUTT positive group were lower than those in control group A(P<0.05).There was no statistical significance in trace element levels between HUTT negative group and HUTT positive group,control group A(P>0.05).The level of zinc in VVS group was lower than that in control group A(P<0.05).The levels of zinc,calcium,magnesium and iron in POTS group were lower than those in control group A(P<0.05).The level of magnesium in VVS group was higher than that in POTS group(P<0.05).Binary Logistic regression analysis showed that the decrease of zinc[odds ratio(OR)=0.726,95%confidence interval(CI)0.652-0.807]increased the risk of NMS,and the decrease of calcium(OR=1.772,95%CI 0.639-4.909)and iron(OR=0.472,95%CI 0.090-2.476)had no statistical significance on the occurrence of NMS.When the cut-off value of zinc was 80.09μmol/L,the area under curve(AUC)was 0.800,and the sensitivity and specificity for the diagnosis of NMS were 74.5%and 80.0%,respectively.When the cut-off value of magnesium was 1.33 mmol/L,the AUC was 0.631,and the sensitivity and specificity for the differential diagnosis between VVS and POTS were 67.9%and 59.4%,respectively.Conclusions Zinc deficiency may be related to children and adolescents with NMS.Magnesium may have a clinical value in the differential diagnosis of VVS and POTS.