Used in radiolabeled studies to trace metabolic pathways, particularly in antiviral and anticancer research involving DNA synthesis and nucleoside analogs. The tritium label at the 5-methyl position enables high-sensitivity detection in biological systems, making it valuable for receptor binding assays, pharmacokinetic studies, and investigations of DNA replication mechanisms. Commonly employed to study the uptake, distribution, and incorporation of thymidine into cellular DNA.