Fibromyalgia, quality of life, and thiol/disulfide homeostasis in patients undergoing hemodialysis: A multicenter cross-sectional study

Fibromyalgia syndrome (FMS) is a common but frequently overlooked cause of chronic pain in patients with chronic kidney disease, particularly those undergoing hemodialysis (HD). In addition to its impact on quality of life (QoL), FMS may be associated with oxidative stress pathways involved in chronic kidney disease pathophysiology. However, the relationship between FMS and thiol/disulfide homeostasis in HD patients remains unclear. This study examined the association between FMS, QoL, and thiol/disulfide parameters in a multicenter HD population. In this multicenter cross-sectional study, 126 HD patients (66 with FMS and 60 without FMS) from 2 dialysis centers in Turkey were evaluated between July and December 2024. FMS was diagnosed using the 2016 American College of Rheumatology criteria. Demographic data, laboratory parameters, QoL measures (short form-36 [SF-36], Fibromyalgia Impact Questionnaire [FIQ], Brief Illness Perception Questionnaire), and oxidative stress markers (native thiol, total thiol, disulfide, and related ratios) measured by automated spectrophotometry were analyzed. Group comparisons were performed using appropriate statistical tests. Correlations were assessed using Spearman analysis. Multivariable binary logistic regression was conducted to identify variables independently associated with FMS. Post hoc power analysis demonstrated adequate statistical power (87.3%, α = 0.05). Native thiol (242.35 ± 40.45 vs 225.36 ± 40.01 μmol/L, P = .019), total thiol (284.39 ± 46.60 vs 264.76 ± 46.29 μmol/L, P = .019), and disulfide (21.02 ± 3.74 vs 19.70 ± 3.62 μmol/L, P = .047) levels were higher in patients with FMS, whereas thiol/disulfide ratios did not differ between groups. FMS patients had significantly higher FIQ scores and lower SF-36 domain scores, indicating poorer QoL. Weak correlations were observed between native thiol and FIQ (r = 0.202) and between total thiol and SF-36 mental health (ρ = -0.242). In multivariable analysis, total thiol remained independently associated with FMS (OR = 1.009, P = .023), although explained variance was modest (Nagelkerke R2 = 0.058). FMS in HD patients is associated with impaired QoL and modest alterations in thiol-related oxidative parameters without a shift in thiol/disulfide ratios. These findings should be interpreted cautiously given the cross-sectional design. Prospective studies are needed to clarify underlying mechanisms.