Study to Evaluate 13 C Isotope Ratio Measurement for Urea Cycle Capacity Assessment

In this short-term study a method for the evaluation of the metabolic competency of the urea cycle in vivo will be assessed. In order to monitor the efficacy of new treatment options for patients with urea cycle disorders and to monitor the severity of the disease, a reliable and safe quantitative method for the measurement of the urea cycle flux is required. Urea synthesis will be evaluated by administering sodium \[1-13C\]-acetate and measuring subsequent incorporation of \[13C\] label from Na-acetate into urea in healthy volunteers and asymptomatic subjects genetically disposed to urea cycle disorders.