[Blood level of tryptophan in psychiatric diseases].

The dosage of the free tryptophan and of the total tryptophan is interesting in psychiatric diseases when a possible role of serotonin is suspected: endogenous melancolia, schizophrenia, sleep disorders. The dosage of tryptophan is made by ultracentrifugation and separation then spectrofluorimetry by increasing 15 times the native fluorescence of tryptophan. The data are given for 16 healthy volunteers and 12 schizophrenics treated and not treated. The methodology of sampling is described and must be strictly standardized to get interpretable data.