Correlation of serotonin levels in CSF, platelets, plasma, and urine

► An improved method of measuring serotonin levels was developed. ► Levels of serotonin in CSF and platelets were highly correlated in humans (r = 0.97). ► First study to show high correlation of serotonin in CSF and blood in humans ► Levels of serotonin in CSF and platelets were highly correlated in rats (r = 0.97). ► Lower correlations were found for serotonin in CSF vs. plasma or urine.