Gradients of concentrations of tryptophan and 5-hydroxyindoleacetic acid (5-HIAA) in cerebrospinal fluid (CSF).

CSF from neurological and other patients was analyzed for its content of tryptophan, 5-HIAA and homovanilic acid (HVA). The gradients of concentration of these substances from ventricular spaces to lumbar sac indicate that tryptophan and 5-HIAA probably enter the CSF from all levels of the nervous system, but that HVA originates entirely in the brain. A study of CSF tryptophan in patients with hepatic cirrhosis provided no support for theories which implicate abnormal tryptophan metabolism as a cause of hepatic coma.