Difference in the concentration of tryptophan metabolites between maternal and umbilical foetal blood.

Maternal and umbilical foetal blood at delivery were analysed for tryptophan metabolites by using fully automated high-performance liquid chromatography. The metabolites detected in 100 microliters of maternal plasma were kynurenine, serotonin, 5-hydroxyindoleacetic acid, indolelactic acid, indoleacetic acid and indolepropionic acid. These metabolites were present in various amounts in the protein-bound form. Except for indolepropionic acid, the concentrations of tryptophan metabolites were significantly higher in umbilical foetal plasma than in maternal plasma. In addition, 3-hydroxyanthranilic acid was present in umbilical foetal blood, but not in maternal blood. Furthermore, kynurenic acid was also detected in amniotic fluids.