Urea 13C is a urea molecule radiolabelled with the non-radioactive element carbon-13. 13C-urea present in drugs which are intended for use in the qualitative detection of 13CO2 in whole blood specimens, collected after the ingestion of 13C-urea. Helicobacter pylori (H. pylori) organisms colonizing the lining of the human stomach, produce urease which converts 13C-urea into 13CO2 and ammonia (NH4+). In the presence of urease associated with gastric H. pylori, 13C-urea is decomposed to 13CO2 and ammonia NH4. The 13CO2 is absorbed in the blood, then exhaled in the breath. This results in an increase in the ratio of 13CO2 to 12CO2 in a TEST breath sample compared to a BASELINE sample.