Estriol-d2（Cat No.:R067692）is a deuterium-labeled form of estriol, a naturally occurring estrogen primarily produced during pregnancy. Incorporating two deuterium atoms, estriol-d2 is chemically and biologically similar to native estriol but allows for precise detection in mass spectrometry-based assays. It is commonly used as an internal standard in pharmacokinetic, hormone profiling, and endocrine research. Estriol-d2 aids in tracking estrogen metabolism, monitoring hormone replacement therapy, and studying estrogen-related disorders. Its stable isotope labeling ensures accurate quantification without altering the compound’s biological function, making it essential for analytical and clinical research applications.