Factors influencing free serotonin in human plasma.

Abstract The influence of cortisol on the relation between plasma-free and platelet-bound serotonin in venous blood was examined in patients with rheumatoid arthritis treated with cortisone in excess and in patients not treated with cortisone, as well as in a normal person after i.v. injection of 50 mg cortisol. The correlation between ceruloplasmin and plasma-free or platelet-bound serotonin was investigated in patients with Wilson's disease. Cortisone significantly reduced the increased free serotonin level in rheumatoid arthritis. Patients with Wilson's disease had normal plasma-free serotonin levels, indicating that a low value of ceruloplasmin does not produce increased plasma-free serotonin levels. Platelet-bound serotonin values were diminished in these patients.