C-13 breath tests: Visions and realities

Breath tests have been used in research laboratories for over 25 y. Origina lly, the tests were based on the use of C-14, rather than on the nonradioac tive isotope,C-13. When C-13 became widely available at a reasonable cost, research groups in the United States and Europe developed methodologies to measure C-13 abundance in samples of CO2. The tests used a variety of subst rates and measured pancreatic function, fat absorption, bacterial overgrowt h and P-450 mixed-function oxidase, Thus far, the only test to be approved by the Food and Drug Administration is the C-13-urea breath test. This manu script describes the process by which approval is gained, and indicates the steps necessary for other tests to receive Food and Drug Administration ap proval.