Insulin, plasma aminoacid imbalance, and hepatic coma

It is proposed that severe impairment of liver function in cirrhosis or portacaval shunt results in unrestricted entry of insulin into the peripheral circulation. The ensuing high level of insulin promotes excessive removal of the branched-chain aminoacids by muscle, thereby lowering the plasma levels of these aminoacids. In consequence, the competitive action of the branched-chain aminoacids on the entry of tryptophan into the brain is reduced, more tryptophan enters the brain, and serotonin is synthesised in excess, thus facilitating hepatic coma.