Affiliations: Children's National Medical Center, The George
Washington University, Washington DC, USA | Children's Hospital of Philadelphia, Department of
Pediatrics, University of Pennsylvania School of Medicine, Philadelphia, PA,
USA
Note: [] Corresponding author: Nicholas Ah Mew, Children's National
Medical Center, Division of Genetics and Metabolism, 111 Michigan Avenue,
Washington DC 20010, NW, USA. Tel.: +1 202 476 5863; Fax: +1 202 476 2390;
E-mail: nahmew@childrensnational.org
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.
Keywords: Stable isotopes, urea cycle disorders, ureagenesis, mass spectrometry
