Premium
Changes in gastric environment with test meals affect the performance of 14 C‐urea breath test
Author(s) -
PATHAK CHANDER M,
BHASIN DEEPAK K,
NADA RITAMBARA,
BHATTACHARYA ANISH,
KHANDUJA KRISHAN L
Publication year - 2005
Publication title -
journal of gastroenterology and hepatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.214
H-Index - 130
eISSN - 1440-1746
pISSN - 0815-9319
DOI - 10.1111/j.1440-1746.2005.03885.x
Subject(s) - urea breath test , medicine , gastric emptying , urea , gastroenterology , citric acid , meal , breath test , capsule , helicobacter pylori , zoology , rapid urease test , helicobacter pylori infection , stomach , food science , chemistry , biochemistry , botany , biology
Background: 14 C‐urea breath test (UBT) is considered to be an accurate diagnostic test for the detection of active Helicobacter pylori infection. Various test meals are used in 14 C‐UBT to slow down gastric emptying, and to enhance the gastric distribution, in order to increase the time and area of contact between microorganisms and the tracer substrate. The aim of the present paper was to evaluate the effect of gastric environment on the performance of 14 C‐UBT using an alkaline and an acidic liquid test meal having gastric emptying retardant effect. Methods: The comparison of 14 C‐UBT was done with liquid test meals (200 mL water) comprising (i) plain drinking water (PDW); (ii) 1.3 g or 3.0 g citric acid (CA); and (iii) 3.0 g trisodium citrate (TSC). Eighteen patients (37 ± 12 years, range 18–57 years) with complaints of dyspepsia participated in the study. The status of H. pylori was confirmed by histology and rapid urease test. A total of 93 kBq of 14 C‐urea (0.5 mL) in a gelatin capsule was orally administered along with liquid test meals to the overnight fasting subjects. Breath samples were collected and radioactivity measured. Results were expressed as 14 CO 2 /mmol exhaled CO 2 as percentage of administered radioactive urea. Results: Higher acidic gastric environment (pH approx. 2.0) with CA was found to increase the exhaled 14 CO 2 level in a dose‐dependent manner as compared to PDW and TSC meal ( P < 0.05) at all time points. With TSC test meal, the expired 14 CO 2 level decreased in the lower acidic gastric environment (pH approx. 5.3). The peaks of exhaled 14 CO 2 with TSC test meal were observed at the same time points as that with PDW and CA test meals. The 14 C‐UBT with TSC was found to be positive in 77% of patients (10/13). Conclusion: Better interaction between the microbial urease and 14 C‐urea, caused by a test meal that retards gastric emptying and that changes gastric pH, plays an important role in hydrolysis of the administered 14 C‐urea by H. pylori urease. © 2005 Blackwell Publishing Asia Pty Ltd