超微剂量^14C—尿素呼气试验诊断幽门螺杆菌感染

Super microdose 14 C urea breath test for the diagnosis of Helicobacter pylori infection

目的探索１８５ｋＢｑ１４Ｃ尿素呼气试验（ＵＢＴ）诊断幽门螺杆菌（Ｈｐ）的可行性及ＵＢＴ计数与Ｈｐ定量及炎症的关系．方法共１６１例，ＵＢＴ在内镜检查前进行，继１８５ｋＢｑ１４Ｃ尿素溶液吸服２０ｍｉｎ后采集呼出气标本；再吸饮３７ｋＢｑ１４Ｃ尿素溶液，１５ｍｉｎ后再收集标本；测定１４ＣＯ２活性．内镜下取胃窦、胃角及胃体粘膜活检，分别作尿素酶试验、培养、组织Ｇｉｅｍｓａ染色诊断Ｈｐ及病理学检查（ＨＥ染色）判定炎症，任一部位任两项阳性者判为Ｈｐ阳性，３个部位均阳性为（＋＋＋），２个部位阳性为（＋＋），仅１个部位阳性为（＋），炎症分级参照此标准．结果胃粘膜活检Ｈｐ阳性者８３例（５１６％），ＵＢＴ诊断Ｈｐ的敏感性和特异性分别９４０％和９７４％；Ｈｐ（＋＋＋）与Ｈｐ（＋）组间有显著差异（Ｐ＜００５），但炎症程度与活动性与ｍｉｎ－１无明显相关（Ｐ＞００５）．结论１４ＣＵＢＴ是诊断Ｈｐ高度敏感和特异的方法，其计数和Ｈｐ定量之间有良好的相关性，而与胃粘膜炎症无关．

AIM To evaluate the feasibility of 18 5 kBq of 14 C urea breath test(UBT)for the diagnosis of H.pylori and its relationship with H.pylori load and inflammation in gastric mucosa. METHODS One hundred and sixty one patients (male 112, aged 20-70 years) received 14 C UBT before endoscopy. Of them, 57 were diagnosed as having duodenal ulcer, 5 gastric ulcer, 5 erosive gastritis and 94 chronic gastritis. Biopsies from the antrum, angula and corpus(3 spot)were taken for H.pylori detection by the urea test, culture and modified Giemsa staining. Inflammations were diagnosed by HE stain. H.pylori was graded as “ +++ ” if the 3 spots were all H.pylori positive, “ ++ ” if 2 of the spots were positive, and “+” if only 1 spot was positive. The inflammation was graded with reference to H.pylori grading. The expired air sample was collected by 0 5mmol/L of hyamine methyl solution at 20 min after the administration of 18 5kBq of 14 C urea solution. Another 37kBq of 14 C urea solution was administered and sample was taken after 15 min. Ten milliliters of scintillation solution were added to the sample and 14 CO 2 activity was measured in the liquid scintillation counter. The results were expressed as count per minute (min -1 ). The cut off value was determined by the mean min -1 of the H.pylori negative patients plus 3 standard derivations (for 18 5kBq 14 C UBT)or plus 2s (for 37kBq 14 C UBT). RESULTS Eighty three patients were H.pylori positive in biopsy (51 6%). The cut off values were 90min -1 and 200min -1 for 18 5kBq and 37kBq 14 C UBT,respectively. For 18 5kBq 14 C UBT,the sensitivity, specificity, PPV and NPV were 93 4%,97 4%,97 5% and 93 8%. There was a significant difference in min -1 counting between H.pylori “+” and “+++” when 18 5kBq 14 C urea was used ( P <0 05) . No significant difference was observed in min -1 counting between the inflammation grading both in the chronic and acute inflammation ( P >0 05) . CONCLUSION UBT using 18 5kBq 14 C urea is highly sensitive and specific for the detection of H.pylori infection with the advantage of better dose effect ratio than that of 37kBq 14 C UBT and will be worthwhile for its clinical use. The results suggest that min -1 counting of UBT is well relevant to the H.pylori loaded in the stomach and might be used as a quantitative test for H.pylori infection.