体外模拟胃肠道消化环境对免疫法粪便隐血实验的影响

Effect of in vitro gastrointestinal environment on immunochemical fecal occult blood test

目的探讨胃肠道消化环境对粪便隐血检测的影响。方法采集中日友好医院2015年体检中心25名健康志愿者外周混合静脉血共45 ml，建立胃肠道体外模拟消化模型，采用两种免疫法便隐血检测试剂，研究不同消化时间及消化液浓度对免疫法便隐血检测的影响。结果出血量〉5 ml时，胃液消化3 h且肠液消化2 h便隐血实验仍为阳性；胃液消化0.5～3 h后如继续肠液消化3 h以上时便隐血实验转为阴性；粪便隐血实验的阳性率与出血量密切相关，当出血量较大较急时，由于后带现象可出现假阴性；2种试剂的检出上限均超过3 165 ng/L，检出下限为0.2 ng/L。结论免疫法检测粪便隐血不仅对下消化道出血敏感，对上消化道出血也有较高的阳性率，免疫法便隐血试剂检出限范围较宽，能够满足临床便隐血检测需要。

ObjectiveTo investigate the effect of gastrointestinal environment on fecal occult blood test.MethodsMixed peripheral venous blood （45 ml） of 25 healthy volunteers from medical examination center of China-Japan Friendship Hospital in 2015 were collected to establish an in vitro gastrointestinal digestion model. The model was used to study the effects of different digestion time and concentration of digestive juice on the immunochemical fecal occult blood test using two kinds of occult blood detection reagents.ResultsWhen the amount of bleeding was over 5 ml, fecal occult blood test still showed positive after artificial stomach liquid digestion for 2 hours and artificial intestinal liquid digestion for 5 hours.The fecal occult blood test turned negative after artificial stomach liquid digestion for 0.5-3 hours and artificial intestinal liquid digestion for 3 hours. The positive rate of fecal occult blood test was closely related to the amount of bleeding. When the amount of bleeding was large and bleeding was acute, false negative could be caused by postzone phenomenon. The upper detection limit of two reagents was more than 3 165 ng/L, and the lower detection limit was0.2 ng/L.ConclusionsHigher positive rate was detected not only in lower digestive tract bleeding but also in upper gastrointestinal bleeding with immunoassay method. Immunochemical fecal occult blood reagent had a wide detection range and could meet the clinical requirements for detection of gastrointestinal bleeding.