Variations of urinary creatinine and its correlation to excretion of indole metabolites in mental patients

The daily creatinine excretion was found to be quite variable in hospitalized schizophrenic patients and mental defectives. The variability was not related to dietary factors. A strong correlation between the daily output of creatinine and tryptamine was observed under a variety of experimental conditions. Weaker, but positive correlations were found between the daily excretion of creatinine and 3-indoleacetic acid or 5-hydroxyindoleacetic acid. The relationship between these findings and psychotic episodes in schizophrenic patients is discussed. It is suggested that expression of urinary constituents per unit weight of creatinine may obscure important metabolic variations in mental patients.