Arginine availability appears to play a very interesting role in how it affects the creatine synthetic pathway. For example, in arginase deficiency, high levels of arginine have been implicated in causing elevated guanidino compounds, which is thoughtÂ to play a role in neurologic abnormalities. Conversely,Â Boenzi et al. (JIMD Volume 35, Number 4 (2012), 647-653) recently reported that potential arginine depletion caused by variousÂ urea cycle defects is correlated to low creatine levels. Measuring creatine and guanidinoacetate in these disorders could prove to be a useful clinical monitoring tool to optimize treatment.
Hilary Vernon, MD PhD