The role of tryptophan, 5-hydroxy indole-3-acetic acid and their protein binding in uremic patients.

An on-line high performance liquid chromatography (HPLC) method of analysis with electrochemical detection was developed to quantitate catecholamines, tryptophan (Trp) and 5-hydroxy indoleacetic acid (5-HIAA) in muscle and plasma samples from healthy subjects and uraemic patients undergoing continuous ambulatory peritoneal dialysis (CAPD). Equilibrium dialysis was performed on the plasma samples from 14 healthy and 14 uraemic subjects for the separation of free Trp and its metabolites from bound Trp. The results demonstrate abnormal Trp-albumin binding probably with accumulation of indolic metabolites and abnormally high muscle Trp concentration in uraemic patients.