K Sunny Joseph, Garcia Cesar J, McCallum Richard W
Division of Gastroenterology (JS, CJG), Hepatology and Nutrition, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center, El Paso, Texas.
Department of Internal Medicine (RWM), Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center, El Paso, Texas; Center for Neurogastroenterology and GI Motility (RWM), Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center, El Paso, Texas.
Am J Med Sci. 2016 Mar;351(3):229-32. doi: 10.1016/j.amjms.2015.12.008.
Based on literature review, a positive lactulose breath test (LBT) for small intestinal bacterial overgrowth requires an initial peak value of hydrogen within 100 minutes of lactulose ingestion with a second peak before 180minutes. However, using scintigraphic monitoring of lactulose transit time, mean oral-cecal arrival time has been reported as 73minutes. The goal was to propose new criteria for analysing the LBT to overcome false positive interpretations.
LBTs from our referral center were interpreted as positive after ingestion of 10g of lactulose using the following approach for hydrogen concentrations: (1) The literature guidelines: greater than 20ppm from a baseline less than 10ppm achieved within 100minutes followed by a further rise of greater than 15ppm within 180minutes. (2) The proposed criteria: greater than 20ppm from a baseline less than 10ppm within either 60 or 80minutes followed by a further rise of greater than 15ppm during the 180-minute test.
A total of 153 patients with symptoms suspicious for small-bowel bacterial overgrowth underwent testing. Of all, 26.1% patients tested positive by 100minutes, 11.8% patients tested positive by 60minutes and 18.3% patients tested positive by 80minutes. The percentage of positive LBTs at 60 and 80minutes was significantly lesser than for the 100minutes criteria (P < 0.05).
The first hydrogen peak increase should occur by either 60 or 80minutes to increase the specificity of LBT for small intestinal bacterial overgrowth based on the reality of lactulose cecal arrival times.
基于文献综述，小肠细菌过度生长的乳果糖呼气试验（LBT）呈阳性，要求在摄入乳果糖后100分钟内氢气初始峰值出现，且在180分钟前出现第二个峰值。然而，通过闪烁扫描监测乳果糖通过时间，据报道平均口腔至盲肠到达时间为73分钟。目的是提出分析LBT的新标准，以克服假阳性解读。
我们转诊中心的LBT在摄入10克乳果糖后，根据以下氢气浓度方法解读为阳性：（1）文献指南：在100分钟内从基线低于10ppm升至大于20ppm，随后在180分钟内进一步升高大于15ppm。（2）提议的标准：在60或80分钟内从基线低于10ppm升至大于20ppm，随后在180分钟测试期间进一步升高大于15ppm。
共有153例有小肠细菌过度生长可疑症状的患者接受了检测。其中，26.1%的患者在100分钟时检测呈阳性，11.8%的患者在60分钟时检测呈阳性，18.3%的患者在80分钟时检测呈阳性。60分钟和80分钟时LBT阳性百分比明显低于100分钟标准（P<0.05）。
根据乳果糖到达盲肠时间的实际情况，氢气第一个峰值增加应在60或80分钟内出现，以提高LBT对小肠细菌过度生长的特异性。
