Breath and Blood Ammonia Response to an Oral Protein Challenge

The investigators specific aim is to evaluate the changes in breath ammonia in comparison to blood ammonia and other physiologic markers after a moderate oral protein challenge in healthy subjects and subjects with liver cirrhosis.

Ammonia is an important molecule relevant to numerous diseases, especially to the millions of patients with cirrhosis worldwide. Venous blood ammonia via limb phlebotomy, can at best roughly estimate whole body ammonia, but says little or nothing about intestinal production, and cannot "source" ammonia to any particular organ or body compartment. Unfortunately, there are no presently available better tests. Therefore, despite these acknowledged limitations, venous ammonia the "bronze standard" benchmark by which new metrics are assessed. The present protocol attempts to address both concerns and build upon the investigators prior high protein experience. By using a standard moderate protein challenge, the investigators can evaluate the breath ammonia responsiveness in healthy subjects and those with cirrhosis. This protocol leverages the power of breath research to evaluate responses to oral challenges. This remains a key asset of breath research. Since the protocol proposes a moderate protein challenge, the investigators can evaluate disease states with minimal or no risk. As with past high protein studies, lactulose (10gm) will still be added to provoke a hydrogen response.

Levels of Ammonia (parts per billion) in response to an oral protein challenge using the Bedfont breath monitor