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
