Objective: Fibromyalgia syndrome (FMS) is a chronic disorder associated with severe pain. According to the National Fibromyalgia Association, the prevalence of FMS is between 3% and 6% in the general population, with about 90% of the patients being women. The primary goal of this study was to evaluate the relationship between vitamin D and serotonin levels and FMS severity. Methods: Forty participants with fibromyalgia (mean age: 37.8±9.5 years) were included and had their medical history taken, a physical examination, and laboratory testing in the Rheumatology Department at Al-Ameen Hospital in Taif, Saudi Arabia. The revised Fibromyalgia Impact Questionnaire (FIQR) was used to determine the FMS severity. Results: The results showed that 42.5% of the patients were considered to have mild/moderate fibromyalgia, with the remainder having severe/extreme fibromyalgia. The latter were more likely to have lower serotonin levels. The results showed a significant dose-dependent negative relationship between the serotonin levels and FIQR scores ( P =0.002). However, no significant correlations were found between the vitamin D levels and FIQR scores ( P =0.112). Conclusion: The findings of this study show that the improved health of FMS patients is associated with normal serotonin levels.

Introduction Fibromyalgia syndrome (FMS) is a non-inflammatory, chronic disseminated musculoskeletal pain with unknown etiology. FMS patients suffer from generalized pain that markedly decreases their quality of life and productivity. Objective To investigate the prevalence of FMS and the correlation between people with positive screening criteria for FMS and their socio-demographic characteristics in Taif city. Methodology A cross-sectional study was performed in Taif city, Saudi Arabia, from June 2021 to August 2021. A structured self-estimated electronic questionnaire developed by Google Forms. The questionnaire depended on the 2010 American College of Rheumatology (ACR) criteria. Data analysis was performed by using SPSS, version 21.0 (IBM Corp., Armonk, NY). Result Out of 1015 participants, 77 participants (7.6%) were revealed to have FMS. The prevalence of FMS among females (9.3%) was significantly higher (p<0.001) than that among males (3.1%). In addition, participants aged 40 years old or more showed a significantly higher prevalence of FMS (p=0.003) compared to those aged less than 40 years old (11.7% versus 6.0%, respectively). In addition, occupational status was found to significantly affect FMS prevalence (p=0.040) as the highest prevalence was reported among employees (10.8%) and housewives (9.4%) compared to the unemployed (8.8%), students (5.0%), and retired participants (4.0%). On the other hand, participants’ nationality was shown to have no significant effect on fibromyalgia prevalence (p=0.396). Conclusion Results show a slightly high prevalence rate of FMS in Saudi Arabia. Prevalence was seen greater in women, old age, and employed individuals. Poor knowledge of FMS was seen among the general Saudi population. Educational programs are needed to increase awareness of the disease.