SEROTONIN LEVELS, PAIN THRESHOLD, AND FIBROMYALGIA SYMPTOMS IN THE GENERAL-POPULATION

Objective, To investigate the association of serum serotonin with fibr omyalgia (FM), and to study the relationship of serotonin to clinical variables associated with FM. Methods, Serum samples (n = 292) were ob tained on subjects without pain, with regional pain, and with widespre ad pain during a population survey. The tender point examination was m ade according to American College of Rheumatology examination criteria by an examiner blind to the subjects' complaints. Serotonin was deter mined by high performance liquid chromatography coupled to an electroc hemical detector. Results, No associations between clinical variables and serotonin levels were found in the group as a whole. Subjects with FM had lower serotonin levels unadjusted (p = 0.019) and adjusted for age and sex (p = 0.059) than those without FM. Within the FM group, a ssociations between serotonin and tender point count (r = 0.563) and d epression (r = 0.549) were noted, but the direction of association was opposite to previous reports and expectations. Conclusion, Serum sero tonin levels are significantly lower in persons with FM compared to th ose without FM, but the range of values is wide. Difficult to explain correlations with reversed directions are noted for tender point count , dolorimetry, depression, and anxiety among those with FM. Serotonin is not correlated with any clinical variable's in the general populati on, and separate pain groups cannot be distinguished.