Tryptophan in hepatic coma.

The concentrations of tryptophan in serum and CSF, as well as that of 5-HIAA in CSF were investigated in various group of patients. Those with hepatic cirrhosis have normal total serum tryptophan. However, because of the low concentration of serum albumin the percentage of nonalbumin-bound tryptophan is elevated about 50 percent above the mean control value. By contrast tryptophan in the CSF was increased by 50 to over 800 percent. This suggests that there is also an increase in brain tryptophan and serotonin in the cirrhotic patients. No significant difference was found for the concentrations of tryptophan in CSF of patients in coma and those not in coma. Patients with hepatic coma had an elevated concentration of 5-HIAA in the lumbar CSF which may reflect the increase in this compound and in serotonin reported by Jellinger and Riederer (1977). However, following treatment with probenecid in order to block the egress of 5-HIAA from the CSF, the concentration of 5-HIAA in relation to that of probenecid was not significantly different for the group with hepatic coma as compared with the control group.