New medicines are being developed to treat urea cycle disorders. To better understand if the medicines help restore how the urea cycle works, doctors and researchers need a safe and accurate test to measure how well the urea cycle is working. One way to measure how the urea cycle works is to drink a very small amount of a "labeled" form of ammonia called 15N-ammonium chloride (15NH4Cl). 15NH4Cl will be referred to as "the tracer", this tracer is non-radioactive. We can follow the tracer in blood tests to measure how the body uses and removes ammonia in the urea cycle. The amount of tracer detected in the blood may indicate if the urea cycle is working correctly.

The goal of this study is to use the tracer to measure how well the urea cycle works in both healthy participants and participants with urea cycle disorders.