Variations of Urinary Creatinine and its Correlation to Tryptamine Excretion in Schizophrenic Patients

Abstract

IN the course of investigating the effect of diet 011 behaviour and excretion of urinary constituents in schizophrenic patients a remarkably wide variation in the daily output of creatinine was found in several subjects. We also observed a high degree of correlation between the excretion of creatinine and urinary tryptamine. Both phenomena are shown in Fig. 1, where the daily excretions of creatinine and tryptamine along with urine volume and daily tryptophan intake are plotted over 18 consecutive days for the patient who showed the greatest association of these two variables. During the period of observation the creatinine excretion varied from 0.90 to 1.78 g/24 h with a corresponding range of tryptamine excretion of 45–182 µg/24 h. The correlation coefficients between urinary tryptamine and creatinine as well as that of tryptophan intake are presented in Table 1. Both Fig. 1 and Table 1 show that the variations of tryptamine in the urine are not related to the tryptophan intake, which was maintained between 0.53 and 1.04 g/24 h. A highly significant positive correlation is, however, associated with the excretions of tryptamine and creatinine. During the observation period, the patient received a standardized diet containing 1.0–1.5 g of tryptophan/24 h. Exact records were kept of uneaten food and the actual daily intake of each major food constituent calculated by difference. The same standardized diet was given for two months prior to the collection period in order to stabilize the tryptamine excretion in regard to tryptophan intake. No psychotropic medication had been given during 8 months previous to the experiment.