Plasma tryptophan levels and anorexia in liver cirrhosis.

Objective: Increased brain tryptophan (TRP) availability for serotonin synthesis may play a role in the pathogenesis of anorexia. Since in chronic liver failure, increased plasma and cerebrospinal fluid TRP concentrations are characteristically reported, we hypothesize that also in liver cirrhosis increased brain TRP availability may constitute the pathogenic mechanism of anorexia. To test this hypothesis, the association between anorexia and plasma TRP was investigated.
Methods: Anorexia and plasma amino acid concentrations were evaluated in 16 patients with liver cirrhosis and compared with those obtained in 13 healthy volunteers.
Results: According to a questionnaire, 11 cirrhotic patients were considered as anorectic. In these patients, brain TRP availability was significantly higher than in nonanorectic patients and controls.
Discussion: Increased brain TRP availability is also associated with anorexia in liver cirrhosis, and supports the hypothesis that increased serotonergic activity may constitute the common pathogenic mechanism for anorexia associated with different diseases.