Serum gamma-aminobutyric acid (GABA) levels in patients with hepatic encephalopathy.

Serum levels of the potent inhibitory neurotransmitter gamma aminobutyric acid (GABA) were measured in 10 patients with chronic liver disease and hepatic encephalopathy, 11 patients with chronic liver disease and no evidence of hepatic encephalopathy, 7 patients with end-stage renal disease and 11 healthy volunteers. Serum GABA levels were elevated in all 10 patients with hepatic encephalopathy, 5/11 with liver disease and no encephalopathy and 4/7 renal disease patients. The mean serum GABA level for the encephalopathic patients (0.92 +/- 0.13 microM, mean +/- SEM) was significantly greater than the mean for liver disease patients without encephalopathy (0.48 +/- 0.05 microM, p less than 0.05), renal disease patients (0.46 +/- 0.04 microM, p less than 0.05) and healthy volunteers (0.39 +/- 0.03 microM, p less than 0.001). These results would tend to support the hypothesis that GABA may play a role in the pathogenesis of hepatic encephalopathy.