The correlation between ammonia levels and the severity of hepatic encephalopathy is controversial.
In this study, researchers from the United States prospectively evaluated this correlation in 121 consecutive patients with cirrhosis.
The research team used clinical criteria to diagnose hepatic encephalopathy.
|Ammonia increased with the severity of hepatic encephalopathy.|
|American Journal of Medicine|
They based the severity of hepatic encephalopathy on the West Haven Criteria for grading of mental status.
Arterial and venous blood samples were obtained from each patient.
The team analyzed 4 types of ammonia measurement. These were arterial and venous total ammonia, and arterial and venous partial pressure of ammonia.
They also calculated Spearman rank correlations.
The researchers found that of the 121 patients, 25% had grade 0 encephalopathy, 22% had grade 1, 19% grade 2, 23% grade 3, and 11% had grade 4.
They determined that each of the 4 measures of ammonia increased with the severity of hepatic encephalopathy.
Dr Janus Ong’s team concluded, “Ammonia levels correlate with the severity of hepatic encephalopathy”.
“Venous sampling is adequate for ammonia measurement.”
“There appears to be no additional advantage of measuring the partial pressure of ammonia compared with total ammonia levels.”