RESUMEN
To define the relationship between vitamin D deficiency and fibromyalgia syndrome. This is a prospective cohort study for description of a medical disorder. The study was carried out in Sultan Bin Abdulaziz Humanitarian City, Riyadh, Kingdom of Saudi Arabia from May 2007 to March 2010. One hundred women suffering from fibromyalgia syndrome were included. Blood level of 25-hydroxyvitamin D [25[OH] D] was estimated at initial visit and every 4 weeks until its level exceeded 50 ng/mL. The patients with vitamin D deficiency were treated with ergocalciferol 50,000 IU once weekly until their blood level of 25[OH] D exceeded 50 ng/mL. The number of tender points and the revised Fibromyalgia Impact Questionnaire [FIQR] score were used to assess the fibromyalgia before and after vitamin D repletion. Among the 100 fibromyalgia women, there were 61 women with 25[OH] D deficiency; with vitamin D supplementation, only 42 women showed a significant improvement when their blood level of 25 [OH] D became >30 ng/mL, this improvement became more significant when their blood level of 25[OH] D exceeded 50 ng/ mL. Vitamin D deficiency has to be considered in the management of fibromyalgia syndrome