Serum 25-OH vitamin D levels in patients with fibromyalgia

Background: The association between low levels of 25-hydroxyvitamin D and non-specific musculoskeletal pain, including fibromyalgia syndrome, is controversial. Several studies have reported a "positive association" and two others found "no association." Objectives: To test levels of 25OHD in patients with fibromyalgia syndrome and in matched controls. Methods: The study population comprised 68 premenopausal women with a diagnosis of fibromyalgia and 82 age-matched premenopausal women without. The former were identified from the computerized medical databases of five primary care urban clinics in the south of Israel, and the control subjects were attending the participating clinics for regular periodic blood tests. For each patient, the matched control interview and blood test were performed within a week or two from the patient's interview and blood test, thus controlling for expected seasonal variations. Results: Serum 25OHD was measured using different cutoff levels and compared between the groups (< 30 ng/ml, < 20 ng/ml and < 15 ng/ ml). No statistically significant differences were found between the groups regardless of the cutoff level used. A logistic regression model for predicting women with 25OHD levels < 20 ng/ml showed that all the variables examined in both groups (age, country of birth, education) were not statistically significant. We found the expected seasonal variations of 25OHD levels, though these were not statistically significant. Conclusions: We found no association between fibromyalgia and low 25OHD levels as previously suggested in other studies.