甲烷氢呼气试验也称为乳果糖呼气试验。小肠内不存在水解乳果糖的酶，乳果糖摄入后仍以完整的分子进入结肠，结肠内有大量的细菌，细菌发酵乳果糖产生氢气、二氧化碳和甲烷，其中大部分由肛门排出，15%-50%经结肠壁弥散入血，随血循环至肺部呼出。序贯检测呼气中的甲烷、氢气的量，我院消化内科何兴祥教授团队于2017年开展该项检查，在临床应用中发现：有结肠息肉的病人甲烷氢呼气试验阳性率明显高于无息肉的病人，利用甲烷氢呼气试验可以预测结肠息肉的存在。其研究成果（Ability of lactulose breath test results to accurately identify colorectal polyps through the measurement of small intestine bacterial overgrowth）发表在World Journal of Gastrointestinal Surgery国际专业杂志上（JCR二区杂志）。

甲烷氢呼气试验（lactulose breath test，LBT）是一种测量消化道细菌的间接方法，它主要用于支持小肠细菌过度生长（small intestine bacterial overgrowth，SIBO）的诊断，但在本研究中作为一种筛查结肠息肉的新方法。

纳入2017年~2019年382名进行LBT检测的患者，这些患者经结肠镜检查和病理检查证实是否存在大肠息肉及息肉病理性质，将其分为息肉组和非息肉组。第一，研究结肠息肉、肠道屏障功能损伤（IBFD）与LBT之间的关系，息肉组LBT阳性率显著高于非息肉组LBT阳性率（分别为 41% vs 23%，P < 0.01;71% vs 59%，P < 0.05）。且当LBT阳性时，大肠息肉患者的肠道屏障功能指标脂多糖水平显著高于无息肉患者脂多糖水平（15% vs 5%，P < 0.05），IBFD在结肠息肉患者中比无息肉患者中更容易发生。第二，进一步研究LBT结果与息肉病理性质之间的关系，在摄入乳果糖90 min，腺瘤组和炎症/增生性息肉组患者的H峰值显著高于非息肉组（分别为p <0.01和p=0.03）。第三，研究LBT评估结肠息肉准确性，经过年龄和性别调整后，进行回归分析发现，使用普通甲烷峰值或根据北美LBT阳性共识规定的氢气和甲烷联合值的模型对大肠息肉的预测效果最好，模型的灵敏度≥0.67，特异性≥0.64，准确度≥0.66。以上结果说明LBT具有作为预测大肠息肉的无创筛查工具的潜力。

Table 1 研究对象的一般情况和疾病说明, n (%)

Values presented as mean ± SD, or n (%) of observations. P values were from one-side Fisher exact statistics, with bold font for those less than 0.05. FGID:Functional gastrointestinal disorders; GERD:Gastroesophageal reflux disease; IBS:Irritable bowel syndrome; PU:Peptic ulcer.

Table 2 息肉和非息肉组之间的LBT阳性情况

aP<0.05, polyps vs non-polyps.

SIBO: Small intestine bacteria overgrowth.

Table 3 不同病理类型（炎性/增生性息肉、腺瘤性息肉）息肉和非息肉组中甲烷和氢的峰值

aP<0.05 was considered to indicate a statistically significant difference between inflammatory/hyperplastic polyp, adenomatous polyp and non-polyp groups.

bP<0.05 was considered to indicate a statistically significant difference between inflammatory/hyperplastic polyp and non-polyp groups or between adenomatous polyp and non-polyp groups. Univariate analysis was performed using the nonparametric tests (Kruskal-Wallis independent samples).

Figure1   227例LBT阳性患者的肠道屏障功能损伤率aThe rate of intestinal barrier function damage (IBFD) by 3 blood assays altogether was marginally higher in polyp group than that in non-polyp group,but no significance, P = 0.13.bIt was significantly different between polyp group and non-polyp group when IBFD defined by lipopolysaccharide alone, P<0.05

Figure 2  调整年龄和性别后预测模型的工作特征曲线. A-G: Each model is for a subset of patient population defined by the cutoffs and the size of the subpopulation showing at the top of each box; H: Model performance with key parameters (area under the receiver operating characteristic curve, accuracy, sensitivity, and specificity).

Table 4 预测大肠息肉模型的性能特点

aP< 0.1 for difference in mean value of lactulose breath test between polyp and non-polyp groups for further assessment.

Rise values are baseline-subtracted peak values during the tests. Bold Pvalues indicate the 7 best models in further assessment. ppm: Parts per million.

来源：广药大附一消化内科

初审：王媛

审核：林锐锐

审发：庄文斌

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