Lithocholic Acid-d4 is primarily used as an internal standard in analytical chemistry for the quantification of lithocholic acid in biological samples. Its deuterated form ensures accurate and precise measurements in mass spectrometry, particularly in studies involving bile acid metabolism. This compound aids in research focused on liver function, cholestasis, and other metabolic disorders. It is also employed in pharmacokinetic studies to track the distribution and elimination of lithocholic acid in the body. Additionally, it supports the development of diagnostic assays for bile acid-related diseases.