Noninvasive diagnostic methods in environmental medicine: effect monitoring using stable isotopes

Experience of using two stable-isotope-based effect biomarkers is briefly reviewed. New in vivo methods were developed, adopted, validated and used in an effort to meet the desired standards for early effect monitoring methods in environmental medicine and epidemiology, i.e. they should be noninvasive, non-distressing, simple and readily accepted by voluntary test persons, as well as very sensitive and reliable. Certain tests based on stable isotopes may fulfill these requirements. The specific advantages of using stable isotopes are the minimization of the diagnostic drug dose, and the unequivocal recovery of the labelled diagnostic compound and its metabolites from among their unlabelled endogenous forms in the body. Particular interest is focused on: (1) The measurement of liver detoxification capacity using the [13C]methacetin breath test and the [15N]methacetin urine test; (2) The estimation of antral Helicobacter pylori colonization using the [13C]urea breath test and the [15N]urea urine test. The methods were used in a number of environmental–epidemiological studies with defined groups of children, including: Preschool children (n = 130) living near disused industrial plants and waste dumps (methacetin tests); School beginners (n = 3347) suspected of H. pylori colonization (urea tests). Although both tests provided accurate results in the studies and individual environmental–medical diagnosis, it was found that 13C breath test results were less reliable than the corresponding 15N urine test results if the test person was physically active during the test period. Therefore, 15N urine tests should be preferred whenever monitoring investigations based on stable isotopes are undertaken among young children. Copyright © 1999 John Wiley & Sons, Ltd.