Which analyte is used as a prognostic indicator for liver failure?

Ammonia is commonly used as a prognostic indicator for liver failure because it is a byproduct of protein metabolism that is normally converted to urea in the liver. In cases of liver dysfunction or failure, the liver's ability to convert ammonia to urea is impaired, resulting in elevated levels of ammonia in the bloodstream. High ammonia levels are associated with hepatic encephalopathy, which indicates worsening liver function and poor prognosis. Monitoring ammonia can provide important insights into the severity of liver impairment and help guide treatment decisions.

Other analytes, while they can provide information regarding liver function and overall health, do not serve as specific prognostic indicators for liver failure in the same way. For example, uric acid levels can be elevated due to various conditions but do not specifically correlate with liver failure. Cortisol is primarily related to stress response and adrenal function rather than liver status. Blood urea nitrogen (BUN) can be increased in the setting of liver disease but is less specific for liver function impairment compared to ammonia levels.