Used as a stable isotope-labeled tracer in metabolic studies to monitor lactate metabolism in biological systems. Enables precise tracking of metabolic pathways such as gluconeogenesis, glycolysis, and the Cori cycle using mass spectrometry or NMR. Employed in clinical and pharmaceutical research to assess tissue metabolism, mitochondrial function, and energy dynamics in diseases like cancer, diabetes, and ischemia. Also utilized in labeled compound synthesis for isotopic enrichment studies and in the development of diagnostic agents.