34例不明原因疑小肠出血的病因诊断--推进式双气囊小肠镜与小肠钡灌检查对比研究

背景:不明原因小肠出血的病因诊断较为困难,不同检查手段的临床实用价值有待进一步探讨.目的:通过对不明原因疑小肠出血患者分别行推进式双气囊小肠镜和小肠钡灌检查,比较两者对小肠出血的病变检出率、病因诊断准确率和临床实用价值.方法:34例不明原因疑小肠出血患者分别接受推进式双气囊小肠镜和小肠钡灌检查.推进式双气囊小肠镜检查的进镜方式分为经口腔和经肛门两种,以首选进镜方式检查后未发现病灶者,择期改换进镜方式再行检查.小肠钡灌检查采用插管式稀钡灌注法.两项检查分别由消化科和放射科医师独立操作并诊断,最后进行汇总分析.结果:在34例行推进式双气囊小肠镜检查的患者中,首选从口腔进镜者22例,其中14例(63.6%)检出病灶;8例未发现病灶者择期再从肛门进镜检查,6例检出病灶.12例首选从肛门进镜者中8例(66.7%)检出病灶;4例择期再从口腔进镜检查,3例检出病灶.推进式双气囊小肠镜检查的病变整体检出率为91.2%(31/34);小肠钡灌检查的病变整体检出率为50.0%(17/34).推进式双气囊小肠镜检查发现的阳性病灶均经活检病理检查、手术探查以及临床治疗和随访结果证实,病因诊断准确率为100%(31/31);小肠钡灌检查的病因诊断准确率为48.4%(15/31).全麻下经口腔进镜推进式双气囊小肠镜检查的患者耐受性最佳,其后依次为非麻醉经肛门进镜、非麻醉经口腔进镜和小肠钡灌检查.所有受检者均未发生严重操作相关并发症.结论:经口腔和经肛门进镜方式结合能使推进式双气囊小肠镜完成对全小肠的检查,其在不明原因小肠出血的病因诊断方面明显优于小肠钡灌检查.小肠钡灌对肠腔狭窄和小肠肿瘤仍是一项较有价值的检查方法,同时可作为选择后续检查方法的筛选性手段.全麻下经口腔进镜推进式双气囊小肠镜检查是一项安全、易为患者接受、病变检出率和病因诊断准确率均较高的小肠疾病检查方法.     

小肠肿瘤诊断:双气囊小肠镜与其他检查手段的对比研究

目的比较双气囊小肠镜与小肠稀钡灌注和胶囊内镜检查在小肠肿瘤诊断中的诊断率和准确率。方法对59例临床怀疑小肠肿瘤患者行双气囊小肠镜检查。其中有34例和17例患者分别同期行插管法小肠稀钡灌注或胶囊内镜检查。检查分别由专职医师独立操作并诊断，最后进行汇总比较。结果34例小肠稀钡灌注检查者中，19例诊断为小肠肿瘤或怀疑小肠肿瘤，诊断率为55．9％，最终经双气囊小肠镜确诊为12例，诊断准确率为63．2％（12／19例）；在15例小肠稀钡灌注阴性者中，双气囊小肠镜发现肿瘤3例。17例胶囊内镜检查者中，8例检查结果为小肠肿瘤或怀疑小肠肿瘤，诊断率为47．1％，最终经双气囊小肠镜确诊为4例，诊断准确率为4／8例；在9例胶囊内镜阴性者中，双气囊小肠镜发现小肠肿瘤2例。59例患者中，经一侧进镜检查后（经口或经肛）发现小肠肿瘤36例，完成双侧检查后发现肿瘤16例。7例患者在双侧检查后未发现任何病变。双气囊小肠镜对小肠肿瘤的检出率为88．1％，并经病理和临床随访确诊。上述三项检查中未见明显的与操作相关的并发症。结论双气囊小肠镜在小肠肿瘤诊断率及准确率方面明显优于小肠稀钡灌注和胶囊内镜检查。     

双气囊小肠镜诊断小肠克罗恩病的作用

目的 探讨双气囊小肠镜在小肠克罗恩病诊断中的作用.方法 对28例疑有小肠疾病者行双气囊小肠镜检查,分析双气囊小肠镜检查对小肠疾病,尤其是小肠克罗恩病的检出率、诊断准确性、患者依从性和不良反应发生率等.结果 28例中,小肠病变总检出率为71.43%(20/28),小肠克罗恩病检出率为21.43%(6/28),占所有检出病变的30%(6/20).6例双气囊小肠镜检查判断为克罗恩病者中,结合病理、治疗效果和临床随访,6例均确诊为克罗恩病,诊断准确率为100%(6/6).结论 双气囊小肠镜检查是一项针对小肠疾病安全、有效的检查方法 ,是诊断小肠克罗恩病较为理想的方法 .     

双气囊小肠镜与胶囊内镜在小肠出血应用中的对比研究

目的比较双气囊小肠镜与胶囊内镜在小肠出血中的病变检出率、病因诊断率、耐受性和安全性,初步探讨双气囊小肠镜对小肠出血的内镜下治疗。方法2006年4月至2009年10月烟台毓璜顶医院消化内科收治的可疑小肠出血患者159例,其中81例患者行双气囊小肠镜检查,首选进镜方式分为经口或经肛2种,首选方式检查后未发现病灶者,日后改换进镜方式再行检查。对活动性出血病灶行内镜下止血治疗。另78例患者行胶囊内镜检查。两组患者分别由专门医师独立操作并诊断,最后进行汇总分析,对比双气囊小肠镜与胶囊内镜的临床应用价值。结果双气囊小肠镜组的病变检出率为95.06%,病因诊断率为82.72%,23例检查时见病变活动性出血,行内镜下止血治疗,21例止血成功,内镜止血成功率为91.30%;胶囊内镜组的病变检出率82.05%,病因诊断率为66.67%。双气囊小肠镜组的病因检出率及病因诊断率均显著高于胶囊内镜组,差异有统计学意义(P0.05)。在耐受性方面,胶囊内镜的耐受性最好,双气囊小肠镜的耐受性依次为:全麻下经肛进镜、全麻下经口进镜、非麻醉经肛进镜、非麻醉经口进镜。所有患者均未发生严重并发症。结论双气囊小肠镜对小肠出血的病因诊断明显优于胶囊内镜,并且可行内镜下止血治疗,是一项安全、有效的临床诊疗方法。     

双气囊小肠镜在诊断小肠克罗恩病中的价值

目的 探讨双气囊小肠镜在诊断小肠克罗恩病中的价值.方法 对65例临床怀疑小肠克罗恩病的患者进行检查,并与先前进行的插管法小肠钡灌肠和胶囊内镜检查结果进行对比分析.结果 65例患者行双气囊小肠镜检查诊断为小肠克罗恩病58例,并经病理和临床随访确诊.其中45例患者首选从肛门进镜行小肠镜检查,确认克罗恩病34例（75.6%）,另11例后从口腔进镜,发现病变者8例（72.7%）;20例首选经口进镜,检出克罗恩病11例（55%）,另9例患者日后经肛进镜检查中检出5例（55.6%）.先前进行的46例小肠钡灌肠检查中,24例诊断或疑似小肠克罗恩病,诊断率为52.2%,与小肠镜结果比较,符合小肠克罗恩病诊断例数为18例,诊断正确率为75%（18/24）.22例胶囊内镜检查者中,14例诊断或疑似小肠克罗恩病,诊断率为63.6%,最终经双气囊小肠镜确诊的病例数为11例,诊断准确率为78.6%（11/14）.结论 经口和经肛方式结合能使双气囊小肠镜完成对全小肠的检查;双气囊小肠镜是小肠克罗恩病诊断的较为理想的方法,并能对病变范围和严重程度作出正确判断,插管法小肠钡灌肠是一项决定小肠镜进镜方式选择上有价值的筛选性手段.     

双气囊电子小肠镜诊断67例不明原因腹痛的价值

目的 评价双气囊电子小肠镜对不明原因慢性腹痛的诊断价值,探讨小肠病变所致腹痛病因.方法 对2005年6月至2008年6月中南大学湘雅医院67例有慢性腹痛症状,经胃镜、结肠镜、全消化道钡餐、腹部B超及心电图检查阴性的患者行双气囊电子小肠镜检查.结果 67例患者中,36例经肛进镜,19例经口进镜,12例患者接受2次检查分别经口和经肛进镜.41例发现病灶,阳性检出率为61.19%.41例病变包括克罗恩病15例(36.59%),非特异性小肠炎10例(24.39%),肿瘤8例(19.51%),其他病变8例(19.51%).结论 双气囊电子小肠镜对小肠病变所致慢性腹痛具有较高临床诊断价值.小肠克罗恩病、非特异性小肠炎及小肠肿瘤为不明原因小肠源性腹痛最常见病因.     

双气囊小肠镜对小肠疾病的诊断价值

目的评价双气囊小肠镜对小肠疾病的诊断价值。方法使用Fujinon双气囊小肠镜对我院2011年1月～2012年7月间拟诊小肠疾病的186例患者进行检查。43例患者经口进镜检查,69例患者经肛进镜检查,36例患者经口+经肛进镜检查。镜下可疑病变常规进行组织病理活检。结果 186例双气囊小肠镜检查共发现小肠病变164例,阳性率达88.2%。发现小肠肿瘤性病变28例(炎性息肉14例,间质瘤5例,黄色瘤5例,错构瘤1例,小肠腺癌1例,十二指肠恶性淋巴瘤1例,胃肠息肉病1例)。小肠炎症性病变108例,其中小肠克罗恩病17例,小肠非特异性炎症91例。小肠寄生虫病5例(包括钩虫、鞭虫)。小肠憩室13例,其中确诊小肠Meckels憩室出血1例。小肠外压性狭窄8例。小肠异物2例,均通过小肠镜异物钳成功取出异物。成功行回盲部溃疡出血小肠镜下钛夹止血治疗1例。尚未发生出血、穿孔、胰腺炎等并发症。结论双气囊小肠镜能安全、准确地检查全段小肠,并能对可疑病变取活检,明显提高了诊断的准确性及阳性率,对小肠疾病的诊断有很大应用价值。     

双气囊小肠镜与胶囊内镜诊断小肠出血病因比较

目的比较双气囊小肠镜和胶囊内镜在小肠出血中的诊断准确率和实用价值。方法24例原因不明的可疑小肠出血患者分别接受双气囊小肠镜和胶囊内镜检查。双气囊小肠镜首选进镜方式分为经口或经肛2种，首选方式检查后未发现病灶者，日后改换进镜方式再行检查。胶囊内镜采用以色列GIVEN公司产品。2种检查方法分别由专门医师独立操作并诊断，最后进行汇总比较。结果24例患者中21例通过小肠镜检查发现病灶，总检出率为87．5％。24例患者行胶囊内镜检查后，有阳性发现者11例(45．8％)，另13例无异常发现。双气囊小肠镜检查发现的阳性病灶均经活检病理和手术探查证实，其病因诊断准确率为87．5％，胶囊内镜诊断准确率为25％。在耐受性评估方面，胶囊内镜和全麻下经口进镜的耐受性最佳，以后依次为非麻醉经肛方式和非麻醉经口方式。所有小肠镜和胶囊内镜检查者中未见操作相关的严重不良反应。结论①经口和经肛方式结合能使双气囊小肠镜完成对全小肠的检查。②双气囊小肠镜在不明原因小肠出血的病因诊断方面明显优于胶囊内镜检查。③胶囊内镜在小肠多节段病变和长段病变的诊断上仍有一定价值。④胶囊内镜和全麻下经口双气囊小肠镜检查是一项易为患者接受的、安全的检查方法。     

双气囊电子小肠镜临床应用初探

目的探讨小肠疾病检查新方法——双气囊电子小肠镜的操作、诊断效果、适应证等问题。方法应用双气囊电子小肠镜对13例疑诊小肠疾病的患者进行双气囊小肠镜检查。分别从口侧或肛侧进镜，利用外套管、内镜前端的双气囊交替充气、放气和交替滑进，推进小肠镜进入小肠检查。记录检查范围、时间、耐受性及病变等。结果13例患者共行小肠镜检查19例次(11例次接受了口侧进镜，8例次接受了肛侧进镜)，每侧进镜术程平均80min。从口侧进镜均达第3～6组小肠，从肛侧进镜达4～6组小肠。发现空肠良性问质瘤1例、空肠淋巴瘤1例、回肠溃疡狭窄及憩室2例、空肠息肉2例、空肠糜烂2例。口侧进镜患者，术中多数出现恶心、消化液自口及外滑管口溢出，偶尔出现一过性轻微腹痛；肛侧进镜患者无明显不适及反应；未出现出血、穿孔等并发症。结论双气囊小肠镜是一种新型小肠疾病检查手段，平均2～3h可检查完所有小肠，进镜迅速。于操作直视下观察病变，通过活检对病变进行定性检查。病变检出率明显优于小肠钡剂造影，具有安全、可控性、直视、图像清晰等优点，适用于无肠粘连及严重脏器功能不全的小肠疾病患者。     

双气囊小肠镜在68例小肠疾病诊断中的价值

目的 评价双气囊小肠镜对小肠疾病的诊断价值及安全性和耐受性.方法 2003年5月至2005年7月,对68例经常规检查无异常发现、疑患小肠疾病患者进行双气囊小肠镜检查,其中不明原因反复消化道出血39例、不完全性小肠梗阻7例、慢性腹痛14例、慢性腹泻8例.结果 68例患者中,36例经口进镜,25例经肛进镜,7例患者分别经口及经肛进镜检查.除3例因肠腔狭窄中止进镜外,其余病例均能检查1/2-3/4的小肠,7例患者结合经口及经肛途径完成全小肠检查.68例患者中41例检出阳性病灶,总阳性率为60.3%;其中不明原因消化道出血阳性率为62.6%（26/39）,不完全性小肠梗阻阳性5例,慢性腹痛阳性率为43%（6/14）,慢性腹泻阳性4例.除11例经口进镜者行异丙芬静脉全身麻醉外,其他经口及经肛进镜患者均能耐受整个检查,未出现出血、穿孔等严重并发症.结论 双气囊小肠镜是一种对小肠疾病诊断价值较高、安全可靠的检查手段.     

胰岛素瘤的解剖分布特点分析

目的胰岛素瘤是最常见的胰腺神经内分泌肿瘤，因其临床表现多样，导致诊断困难。影像学诊断尤其是超声内镜(EUS)在胰岛素瘤的诊断中起着重要作用，拥有较高的敏感性和特异性。本研究拟通过明确胰岛素瘤的解剖分布特点，以期有助于提高影像学的诊断准确率和降低漏诊率，尤其是在教育和培训实践中对于EUS的学习者更具有指导价值。 方法回顾性分析解放军总医院第一医学中心病案资料数据库1993年1月至2019年11月经外科手术、病理确诊为胰岛素瘤的患者的临床资料，检索方法采取搜索术后病理诊断为"胰岛素瘤"的病例，通过查阅病例的方法，提取出胰岛素瘤的大小和解剖分布等数据，进一步分析其特点。 结果共检索到确诊为胰岛素瘤的患者116例，其中，男45例、女71例，年龄13～76岁，平均年龄(44.4±14.85)岁。胰岛素瘤单发110例(94.8%)、多发6例(5.2%)。位置分布：头颈部46例(39.7%)，单发45例、多发1例；体尾部68例(58.6%)，单发65例、多发3例；全胰腺多发2例(1.7%)。病变大小特点：最大径0.4～3.4 cm，平均大小(1.53±0.58)cm。≤1 cm 29例、>1 cm而≤1.5 cm41例、>1.5 cm而≤2.0 cm28例，≤3 cm 15例，>3 cm 3例。年龄与肿瘤的大小相关，≤44岁患者肿瘤平均大小为(1.36±0.51)cm、>44岁患者肿瘤平均大小为(1.70±0.60)cm，P<0.05。头颈部的肿瘤大于体尾部的肿瘤，头颈部肿瘤平均大小(1.66±0.63)cm，体尾部(1.42±0.52)cm，P<0.05。 结论胰岛素瘤在胰腺体尾部较头颈部更好发；绝大多数单发，但可以全胰腺多发；多数小于1.5 cm，肿瘤的大小与患者年龄和肿瘤的解剖分布相关。     

Pathogenesis of carcinoma of the papilla of Vater

Most adenomas and carcinomas of the small intestine and extrahepatic bile ducts arise in the region of the papilla of Vater. In familial adenomatous polyposis (FAP) it is the main location for carcinomas after proctocolectomy. In many cases symptoms due to stenosis lead to diagnosis at an early tumor stage. In about 80%, curative intended resection is possible. Operability is the most relevant prognostic factor. Most ampullary carcinomas resp. carcinomas of the papilla of Vater develop from adenomatous or flat dysplastic precursor lesions. They can be sited in the ampulloduodenal part of the papilla of Vater, which is lined by intestinal mucosa. They also can develop in deeper parts of the ampulla, which are lined by pancreaticobiliary duct mucosa. Intestinal-type adenocarcinoma and pancreaticobiliary-type adenocarcinoma represent the main histological types of ampullary carcinoma. Furthermore, there exist unusual types and undifferentiated carcinomas. Many carcinomas of intestinal type express the immunohistochemical marker profile of intestinal mucosa (keratin 7?, keratin 20+, MUC2+). Carcinomas of pancreaticobiliary type usually show the immunohistochemical profile of pancreaticobiliary duct mucosa (keratin 7+, keratin 20?, MUC2?). Even poorly differentiated carcinomas, as well as unusual histological types, may conserve the marker profile of the mucosa they developed from. These findings underline the concept of histogenetically different carcinomas of the papilla of Vater which develop either from intestinal- or from pancreaticobiliary-type mucosa of the papilla of Vater. Molecular alterations in ampullary carcinomas are similar to those of colorectal as well as pancreatic carcinomas, although they appear at different frequencies. In future studies, molecular alterations in ampullary carcinomas should be correlated closely with the different histologic tumor types. Consequently, the histologic classification should reflect the histogenesis of ampullary tumors from the two different types of papillary mucosa.     

Demonstration of the mechanism of action of biguanides

Summary Palmitic acid oxidation in rat diaphragm homogenate is depressed by biguanide concentrations that are still incapable of inhibiting oxidative phosphorylation. Glucose oxidation is not directly effected by the same biguanide concentrations: however, the inhibitory effect of palmitic acid on glucose oxidation is partly removed by biguanides. Inhibition of fatty acid oxidation, which accounts for most of the metabolic effects caused by these drugs, can be regarded as the fundamental mechanism of action of biguanides. There is some evidence suggesting that these drugs might interact with carnitine, thus preventing long-chain fatty acids from being transported across the mitochondrial membrane to the site of oxidation. Traduzione a cura degli AA.     

Lack of correlation of degree of villous atrophy with severity of clinical presentation of coeliac disease

BACKGROUND AND AIM: Both the clinical presentation and the degree of mucosal damage in coeliac disease vary greatly. In view of conflicting information as to whether the mode of presentation correlates with the degree of villous atrophy, we reviewed a large cohort of patients with coeliac disease. PATIENTS AND METHODS: We correlated mode of presentation (classical, diarrhoea predominant or atypical/silent) with histology of duodenal biopsies and examined their trends over time. RESULTS: The cohort consisted of 499 adults, mean age 44.1 years, 68% females. The majority had silent coeliac disease (56%) and total villous atrophy (65%). There was no correlation of mode of presentation with the degree of villous atrophy (p=0.25). Sixty-eight percent of females and 58% of males had a severe villous atrophy (p=0.052). There was a significant trend over time for a greater proportion of patients presenting as atypical/silent coeliac disease and having partial villous atrophy, though the majority still had total villous atrophy. CONCLUSIONS: Among our patients the degree of villous atrophy in duodenal biopsies did not correlate with the mode of presentation, indicating that factors other than the degree of villous atrophy must account for diarrhoea in coeliac disease.     

血吸虫童虫生长发育及其机制的研究进展

血吸虫童虫是宿主免疫系统攻击的重要靶标,包括皮肤型、肺型和肝门型童虫。宿主分子对童虫生长发育具有重要作用。童虫生长发育机制包括免疫调节、信号转导、性别发育及凋亡等。肌动蛋白、组织蛋白酶、烯醇化酶和葡萄糖基转移酶等分子为血吸虫童虫生长发育的重要分子。本文对血吸虫童虫生长发育及其机制的研究进展做一综述。     

氯硝柳胺悬浮剂的毒性评价

目的评价氯硝柳胺悬浮剂的毒性，为现场大规模应用灭螺提供依据。方法按照中华人民共和国国家标准GB 15670-1995《农药登记毒理学试验方法》和鱼类毒性试验方法进行。结果经口、经皮肤的LDso雌、雄性大鼠均>5 000 mg/kg，经呼吸道的LCso雌、雄性大鼠均>5 000mg/m3，该药经口、经皮肤、经呼吸道毒性均属微毒类药物；兔眼用药后，观察期内无不良反应，对眼无刺激性；皮肤用药后对皮肤无刺激性。与氯硝柳胺原药、氯硝柳胺乙醇胺盐原药和氯硝柳胺乙醇胺盐可湿性粉剂相比，氯硝柳胺悬浮剂对鱼急性毒性最低。结论氯硝柳胺悬浮剂属微毒类药物，对鱼的毒性低于其乙醇胺盐可湿性粉剂，适合于现场应用。     

124例耐多药结核分枝杆菌基因突变特征分析

目的对临床分离的耐多药结核分枝杆菌相关基因的突变特征进行分析。方法对124例耐多药结核分枝杆菌以及50株敏感株的耐药相关基因(包括异烟肼inh A、kat G、oxyR-ahp C间隔区以及利福平rpo B)进行序列测定,分析其基因突变情况。结果异烟肼耐药inh A基因突变率为14.5%;kat G基因突变率为70.2%(87/124),主要位于315位;oxyR-ahp C间隔区突变率为15.3%;inh A、kat G两种基因同时突变率75.0%,三种基因同时突变率为89.5%。利福平rpo B基因突变的检出率高达95.2%,突变主要发生在531、526、516位点。结论我省耐多药菌异烟肼耐药相关基因最常见突变为kat G 315、inh A C-T(-15)、axyR-ahp C间隔区(-10)C-T,利福平为rpo B531、526、516。结合MDR-TB耐药相关基因的特征分析,可以建立一种快速、准确、特异的适合于我省的检测结核菌耐多药性的新方法。     

Assessment of quality of life of parents of children with juvenile chronic arthritis

The aim of the study was to assess the quality of life (QOL) and the psychological status of parents of children with juvenile chronic arthritis (JCA). The QOL, anxiety and depression of the parents of 28 children with JCA were evaluated and compared to those of the parents of 28 healthy children. Mothers of JCA children and mothers of healthy children reported similar QOL. The reported anxiety and depression levels were similar for mothers and fathers in both groups. The parents of children with pauciarticular-type JCA reported lower QOL and higher levels of anxiety and depression than the parents of children with other types, namely polyarticular and systemic JCA. These findings may be explained by the fact that the pauciarticular patients had shorter disease duration and were less frequently seen in the outpatient clinic. The QOL of mothers of children with JCA was found to be slightly impaired in the group of children with pauciarticular JCA. Future larger studies are needed to confirm these results, as the number of subjects in the three groups was rather low. Received: 26 September 2001 / Accepted: 8 February 2002     

Numerical Simulation of the Effect of Rate of Change of Glucose on Measurement Error of Continuous Glucose Monitors

Background

A 5-day in-patient study designed to assess the accuracy of the FreeStyle Navigator® Continuous Glucose Monitoring System revealed that the level of accuracy of the continuous sensor measurements was dependent on the rate of glucose change. When the absolute rate of change was less than 1 mg•dl⁻¹•min⁻¹ (75% of the time), the median absolute relative difference (ARD) was 8.5%, with 85% of all points falling within the A zone of the Clarke error grid. When the absolute rate of change was greater than 2 mg•dl⁻¹•min⁻¹ (8% of the time), the median ARD was 17.5%, with 59% of all points falling within the Clarke A zone.

Method

Numerical simulations were performed to investigate effects of the rate of change of glucose on sensor measurement error. This approach enabled physiologically relevant distributions of glucose values to be reordered to explore the effect of different glucose rate-of-change distributions on apparent sensor accuracy.

Results

The physiological lag between blood and interstitial fluid glucose levels is sufficient to account for the observed difference in sensor accuracy between periods of stable glucose and periods of rapidly changing glucose.

Conclusions

The role of physiological lag on the apparent decrease in sensor accuracy at high glucose rates of change has implications for clinical study design, regulatory review of continuous glucose sensors, and development of performance standards for this new technology. This work demonstrates the difficulty in comparing accuracy measures between different clinical studies and highlights the need for studies to include both relevant glucose distributions and relevant glucose rate-of-change distributions.     

Study of constancy of hydrogen-consuming flora of human colon

The constancy of the hydrogen consuming flora of the human colon was studied in 15 healthy subjects via two measurements obtained 18 to 36 months apart. Hydrogen disappearance rate and the major products of H₂-consuming bacteria, methane and sulfide, were measured during incubation of fecal homogenates with excess hydrogen and sulfate. In 11/15, the hydrogen consumption rate and the predominant hydrogen-consuming pathway (methanogenesis, sulfate reduction, or neither) remained constant. However, major shifts in these pathways were observed in four subjects, with two losing and two gaining the ability to produce methane. Methanogenesis was associated with the highest hydrogen consumption rate. This study demonstrates that clinically unrecognizable, major alterations of the colonic flora occur in healthy subjects. Understanding of the factors responsible for these alterations might allow for therapeutic manipulation of the colonic flora.Supported in part by the Department of Veterans Affairs and NIDDKD RO1 DK 13309-25.