Breath sample collection through the nostril reduces false-positive results of 13C-urea breath test for the diagnosis of Helicobacter pylori infection

Influence of urease activity in the intestinal tract on the results of 13C‐urea breath test

“…Many minor modifications of UBT have been reported, including changes in dosage of urea, type of test meals used, timing of sample collection, sampling route, and position of patients. [4][5][6][7][8][9][10][11][12][13][14] A Japanese standard protocol was proposed in 1998 as having high sensitivity and specificity for UBT. 1 In this method, patients who have fasted are given 100 mg of 13 C-urea in 100 mL water and then immediately rinse their mouth with water.…”

“…Twenty minutes is long enough to avoid interference due to urease activity in the mouth. 7,11 Prolonging the time of sample collection to 30 min or later would only decrease the influence of oral urease activity on the results of UBT, whereas there may be a late rise in ∆ 13 CO2 values as a result of small bowel urease activity even in H. pylori -negative patients. According to the Japanese protocol, even when the cut-off value of standard UBT for the diagnosis of H. pylori infection is 2.5‰, a rise in ∆ 13 CO2 values at 20 min may be observed even in H. pylori -negative patients who have both rapid gastric emptying and small bowel bacterial overgrowth.…”

“…In order to eliminate the problem of false positive results in early breath samples, some modifications of UBT have been suggested, such as mouth washing, 7,8 supplying 13 C-urea as a rapid-release tablet, 9,10 or breath sample collection through the nostril. 11 In addition, test meals, including citric acid, were used to slow gastric emptying and enhance the distribution of the substrate within the stomach. 3,5,[12][13][14] Slowed gastric emptying increases the contact time between H. pylori urease and 13 C-urea, resulting in an increased breath 13 CO2 value.…”

An optimized13C-urea breath test for the diagnosis ofH pyloriinfection

“…From each study, the protocol with the best diagnostic performance was selected . Of these, 12 (30%) yielded sensitivities and specificities of 100% [33,37,43,45,47,56,61,63,65,[67][68][69] . Based on the results after reviewing the literature, the present study introduced several variations to simplify even further the technique and make it more cost-efficient, without compromising the high standards of sensitivity, specificity, positive and negative predictive values of the test.…”

“…Later on, doses of 125 [35,72] and 100 mg [36,40,47,48,51,54,57,60,62,65,[73][74][75][76][77][78][79][80][81][82][83] were validated by several American, European and Asian groups, and more recently 75 mg [32,37,[43][44][45]49,50,55,72,[84][85][86][87][88][89][90][91][92][93] , 50 mg [52,56,58,94,95] , 38 mg [96] , 25 mg and even 10 mg [69] of 13 C-urea have proved to be sufficient.…”