Serum levels of gamma-aminobutyric-acid-like activity in acute and chronic hepatocellular disease.

Serum levels of GABA (gamma-aminobutyric acid)-like activity were measured by a radioreceptor assay in 22 healthy subjects and 170 patients with liver diseases. Levels were within normal limits (mean +/- SEM in healthy controls 0.52 +/- 0.04 mumol/l; range 0.2-0.8 mumol/l GABA equivalents) in most patients with uncomplicated acute viral hepatitis, compensated chronic hepatitis, and primary biliary cirrhosis (PBC). In 96% of patients with compensated (non-PBC) cirrhosis levels were slightly high (1.5 +/- 0.06 mumol/l). In 4 patients with decompensated cirrhosis but without hepatic encephalopathy (range 3.0-6.4 mumol/l) and in most of 26 patients with overt hepatic encephalopathy due to acute or chronic hepatocellular failure (range 2.3-18.0 mumol/l) levels were very high. Levels did not correlate closely with the clinical stage of hepatic encephalopathy or with arterial plasma ammonia concentrations. particularly high levels were detected in patients with cirrhosis 12-16 h after gastrointestinal haemorrhages. These findings are compatible with the hypothesis that the GABA neurotransmitter system is involved in the pathogenesis of hepatic encephalopathy in man.