Which condition is most likely to raise ammonia levels significantly?

The condition that most likely raises ammonia levels significantly is an E. coli infection in the gut. This is because certain strains of E. coli can produce urease, an enzyme that breaks down urea into ammonia. The ammonia then gets absorbed into the bloodstream, leading to elevated ammonia levels.

In comparison, while constipation can contribute to increased ammonia levels due to the prolonged breakdown of proteins in the gut, it is not as direct or significant as the effect of an E. coli infection. The acute stress response and dehydration can affect overall metabolism and bodily functions but are less directly related to a rise in ammonia levels. Therefore, the presence of E. coli and its enzymatic activity represents a more potent source for significantly increased ammonia in the body.