Clinical studies of C-13-urea breath test in Japan

The urea breath test (UBT) using isotope carbon is a non-invasive method fo r diagnosing H. pylori infection. In Japan, only C-13-UBT using a stable is otope is available, since the clinical use of radioactive isotope C-14-comp ounds is prohibited. Since there is no worldwide standard protocol for the C-13-UBT, it is therefore important to standardize this test to obtain a ch eap, easy, reproducible method. Factors affecting the outcome of C-13-UBT v alues include sampling times and frequency, the amount of C-13-urea, the cu t-off value, the avoidance of oral urease activity, and changes in gastric emptying times and C-13-urea distribution. Mouth rinsing reduces false-posi tive results due to oral urease activity, particularly within 20 min after ingestion of C-13-urea. A Japanese multicenter trial has shown that the dia gnostic utility of C-13-UBT is superb, with the cut-off value 2.5 parts per thousand in 20-min samples after ingestion of 100mg C-13-urea. The C-13-UB T is a very useful method for diagnosing H. pylori infection.