What happens when the liver cannot convert ammonia to urea?

When the liver cannot convert ammonia to urea, ammonia accumulates in the bloodstream, leading to a condition known as hyperammonemia. This surplus of ammonia poses significant risks, including toxicity to the central nervous system and other organs. The kidneys play a critical role in filtering and excreting waste products, including excess ammonia. Therefore, when there is an overload of ammonia from the liver's inability to process it, the kidneys become increasingly stressed as they attempt to eliminate the excess ammonia. This can lead to potential kidney damage and complications over time.

In contrast, the other options reflect scenarios that are not directly linked to the liver's failure to convert ammonia to urea. The production of excess glucose, maximizing caloric intake, and increased metabolic rates do not specifically relate to the direct implications of ammonia accumulation and are more influenced by various other metabolic processes. Thus, the focus on kidney stress due to the accumulation of toxic substances provides the most relevant connection to the liver's impairment in ammonia conversion.