title: Stable isotopes in the diagnosis and treatment of inherited hyperammonemia.
abstract: Stable isotopes have greatly contributed to our understanding of nitrogen metabolism and the urea cycle. The measurement of urea flux via isotopic methods has traditionally been utilized to determine total body protein synthesis in subjects with an intact urea cycle. However, isotopic studies of nitrogen metabolism are also a useful adjunct to conventional clinical investigations in the diagnosis and management of the inherited hyperammonemias. Such studies offer a safe non-invasive method of measuring the reduction of in vivo hepatic ureagenesis, and thus may provide a more accurate measure of phenotypic severity in affected patients. In addition, isotopic methods are ideally suited to evaluate the efficacy of novel therapies to augment urea production.
authors.affiliation: Children's National Medical Center, The George Washington University, Washington, DC 20010, USA.
authors.forename: Nicholas Ah
authors.initials: NA
authors.lastname: Mew
authors.affiliation: Children's Hospital of Philadelphia, Department of Pediatrics, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA.
authors.forename: Marc
authors.initials: M
authors.lastname: Yudkoff
authors.affiliation: Children's National Medical Center, The George Washington University, Washington, DC 20010, USA.
authors.forename: Mendel
authors.initials: M
authors.lastname: Tuchman
keywords: Stable isotopes; mass spectrometry; urea cycle disorders; ureagenesis