New in vivo tracer method with the use of nonradioactive isotopes and activation analysis.

A method that uses stable, nonradioactive isotopes, as tracers has been developed which is suitable for metabolic studies in newborn infants and pregnant women. The stable tracer is injected, and the samples recovered are activated with thermal neutrons. The isotopes produced are identified and quantitated with their specific emission patterns. Stable Fe/sup 58/, as an example, becomes Fe/ sup 58/ following neutron activation. Standard recovery studies of tracer concentrations of Fe/sup 58/ show reproducible, quantitative results. Simultaneous Fe/sup 58/ and Fe/sup 59/ in vivo plasma clearance s-tudies reveal identical utilization of these isotopes. This technique has potentially broad application in the area of human in vivo kinetic tracer studies. (auth)