Immune markers in fibromyalgia: comparison with major depressed patients and normal volunteers

Background: There is a high degree of comorbidity between fibromyalgia and major depression. The latter is characterized by signs of immune activation, whereas the immune status in fibromyalgia is not yet elucidated. The aims of the present study were to examine (i) neopterin and biopterin excretion in 24-h urine of patients with fibromyalgia compared with normal volunteers and patients with major depression; and (ii) the effects of subchronic treatment with sertraline (11 weeks) on the urinary excretion of neopterin and biopterin. Methods: Measurements of neopterin, biopterin, pseudouridine, creatinine and uric acid in 24-h urine were performed by means of HPLC in 14 fibromyalgia and ten major depressed patients and 17 normal volunteers. Results: There were no significant differences in urine excretion of the above five analytes between patients with fibromyalgia and normal volunteers. Patients with major depression showed significantly higher urinary neopterin excretion than normal volunteers and fibromyalgia patients. Patients with fibromyalgia and major depression had a significantly increased neopterin/creatinine ratio. Fibromyalgia patients had significantly lower urinary excretion of creatinine than patients with major depression. In fibromyalgia patients, there were no significant effects of sertraline treatment on any of the urine analytes. Conclusions: The findings suggest that fibromyalgia, in contrast to major depression, may not be accompanied by activation of cell-mediated immunity. Limitation: Other immune markers should be measured in fibromyalgia before drawing definite conclusions. Clinical relevance: Increased urinary excretion of neopterin can be used as a marker for major depression, but not fibromyalgia.