L-Homocitrulline is primarily used as a biomarker in clinical diagnostics, especially for monitoring urea cycle disorders and liver function. It accumulates in the body when there is a deficiency in enzymes involved in arginine metabolism, making it useful in the diagnosis of conditions like hyperornithinemia-hyperammonemia-homocitrullinuria (HHH) syndrome. In research settings, L-homocitrulline helps in studying metabolic pathways related to amino acid metabolism and nitric oxide synthesis. It is also employed in the development and validation of analytical methods such as mass spectrometry to improve detection sensitivity in metabolic screening. Additionally, its presence in biological samples like blood or urine aids in newborn screening programs to enable early detection of inborn errors of metabolism.