Dynamic thiol and disulphide homoeostasis in fibromyalgia

Introduction: Thiol and disulphide levels are biomarkers that provide useful information about oxidative stress and antioxidant capacity, showing a different homoeostasis in inflammatory and proliferative diseases. We aimed to clarify the possible aetiology of this disease by using thiol and disulphide levels in patients with fibromyalgia, the basis of which has not yet been clearly elucidated. Material and methods: A total of 156 individuals: 86 patients with fibromyalgia and 70 age-matched controls were included in this prospective non-randomised case-control study. Demographic characteristics including smoking status, body mass index (BMI), the duration of complaints, and pain levels were carefully recorded. Dynamic thiol-disulphide homoeostasis in blood samples was determined by an automatic-spectrophotometric method. The Mann-Whitney U and Student's t-test were used to determine the differences between the groups. Results: Sex, BMI, and smoking status were similar between the groups (p = 0.62, p = 0.09, and p = 0.64, respectively). While native thiol levels were found to be high in patients with fibromyalgia (p = 0.018), disulphide levels and the rates of disulphide/native thiol and disulphide/total thiol were significantly low (p = 0.049, p = 0.007, and p = 0.007, respectively). Correlation analysis showed no significant relationship between thiol-disulphide levels and duration of complaints or pain level. Conclusions: Thiol-disulphide balance in fibromyalgia was found to be similar to benign proliferative diseases, suggesting that the underlying mechanism is more likely to be of proliferative pattern rather than inflammatory. Additionally, fibromyalgia is not directly associated with increase in oxidative stress. The molecular mechanisms need to be elucidated.