GLOSSARY

Stable Isotope Tracer is a nonradioactively isotope-labeled material used to follow pathways.

Stable-isotope tracers track material alongside naturally present molecules without radioactive decay of the isotope itself. Enrichment and tracer-to-tracee ratios support a model. Dosing should minimally perturb the system, and label recycling can matter. This is a research method with assumptions, not simply one concentration or a home metabolism-speed test. Interpretation depends on sampling, compartment and steady or changing conditions rather than assuming labeled appearance directly reveals every biochemical destination.

Appearance is entry into a defined pool; disappearance is exit from that pool. They may balance at steady state despite high turnover and constant concentration. Blood uptake is not necessarily oxidation; storage and conversion also count. Dietary and endogenous inputs need separation according to substrate. Model, units and timing are essential for whole-body rates, and one local measurement does not necessarily represent every tissue or resolve all sources of entry.