Blood mercaptan and ammonia concentrations in cirrhotics after a protein load

Measurements of blood ammonia and methanethiol were made in 17 moderate or severe alcoholic cirrhotics without overt hepatic encephalopathy under fasting conditions and 2, 3 1/2 and 5 hours after ingestion of a hamburger containing 80 gm. protein. At every time interval the average blood methanethiol in the cirrhotics was significantly higher than in 11 normal controls. The average blood ammonia in the cirrhotics was also higher than in the controls but only at five hours was the difference statistically significant. Fasting blood ammonia and methanethiol values were not strikingly effective in separating the normals and cirrhotics. After the protein load, however, the peak values of these measurements completely separated the cirrhotics from normals on a two-dimensional plot of methanethiol vs. ammonia. In our sample of patients, the peak postprotein load measurements were not effective in predicting which cirrhotics may develop overt encephalopathy. Utilization of the area under the curve of values obtained after the protein load did not appreciably improve on the results with the single peak value.