Ammonia intolerance - not a predictor of post-shunt encephalopathy

In an attempt to correlate ammonia intolerance with appearance of encephalopathy, 37 cirrhotic patients undergoing an elective portasystemic shunt had a preoperative initial assessment of encephalopathy, an EEG, and oral ammonia tolerance testing. Evaluations were repeated at one week and at two and six months postoperatively. Most patients (32/37) were without chronic encephalopathy and all had either normal or mildly abnormal EEG's preoperatively. No chronic worsening of these indices was seen postoperatively. Early postoperative serum ammonia levels were similar to preoperative values. Late postoperative serum ammonia levels (fasting and after ammonia loading) were significantly increased over those seen in both preoperative and early postoperative periods. While ammonia intolerance may worsen within months of total shunting, it did not correlate with either presence or likelihood of developing chronic encephalopathy.