Metal-induced inflammation triggers fibromyalgia in metal-allergic patients

BACKGROUND: Fibromyalgia (FM) is a disease of unknown etiology. Inflammation could be one of the mechanisms behind this disease. OBJECTIVES: We studied the frequency and clinical relevance of metal allergy in FM patients. METHODS: Fifteen female FM patients were included in the study. Metal allergy was measured by a lymphocyte transformation test, MELISA (R). Ten healthy age-matched women were used as controls for in vitro studies. Reduction of metal exposure in the FM patients was achieved by replacement of dental metal restorations and by the avoidance of known sources of metal exposure. Objective health assessment was performed 5 years after treatment. Subjective health assessment was established by a questionnaire, completed 2, 5 and in some cases 10 years after the start of the study. Follow-up MELISA was also performed. RESULTS: All FM patients tested positive to at least one of the metals tested. The most frequent reactions were to nickel, followed by inorganic mercury, cadmium and lead. Some healthy controls responded to inorganic mercury in vitro but most of the tests were negative. Objective examination 5 years later showed that half of the patients no longer fulfilled the FM diagnosis, 20% had improved and the remaining 30% still had FM. All patients reported subjective health improvement. This correlated with the normalisation of metal-specific responses in vitro. CONCLUSION: Metal allergy is frequent in FM patients. The reduction of metal exposure resulted in improved health in the majority of metal-sensitized patients. This suggests that metal-induced inflammation might be an important risk factor in a subset of patients with FM.