BACKGROUND AND OBJECTIVE: Vitamin D deficiency is an important known responsible factor for development,progression and exacerbation of many musculoskeletal disease.The aim of the present study was to determine the status of serum vitamin D in a number of common musculoskeletal conditions presented an outpatient rheumatology clinic.

METHODS: Pateints with musculoskeletal presentations having  symptoms for at least three months entered the study.Serum vitamin D was determined by assessment of serum 25-hydroxyvitamin D (25-OHD) using ELISA method, and levels less than 20 ng/ml was considered as deficiency. The primary objective of this study was to compare serum 25-OHD level and frequency of 25-OHD deficiency between  patients with musculoskeletal  symptoms and controls.  The secondary objective was to determine the relationship between serum 25-OHD deficiency and musculoskeletal conditions with respect to age and sex.

FINDINGS: 1099 patients (910 females) including 291 (26.47%) patients with knee OA,192 (17.47%) with rheumatoid arthritis (RA), 76 (6.9%) with non-rheumatoid arthritis inflammatory arthritis (NRAIA), 237 (21.56%) patients with nonspecific skeletal pain, 163(14.83%) patients with low back pain (LBP), 114(10.37%) patients with arthralgia,and 26(2.36%) patients with inflammatory back pain (IBP) entered the study to compare with 374 (243 females) controls. Serum 25-OHD levels and frequency of 25-OHD deficiency in knee OA, RA, NRAIA, IBP did not differ significantly with the control group, but in patients with nonspecific musculoskeletal pain and low back pain serum 25-OHD levels were significantly lower than controls. Serum 25-OHD deficiency increased the risk of nonspecific skeletal pain, LBP by 3.9 and 3.32 times respectively (p=0.001 for both). The association was greater in women as compared with men.In patients aged less than 55 years, 25-OHD deficiency increased the risk of knee OA 1.71 times (p=0.014) and the risk of arthralgia 1.84 times (p=0.018).

CONCLUSION: Vitamin D deficiency is significantly related with a number of common musculoskeletal conditions like nonspecific skeletal pain, LBP, arthralgia, according to age and sex. This issue requires further prospective, in particular placebo-controlled studies, to determine efficacy of supplemental vitamin D on skeletal symptoms by comparison of symptoms before and after supplementation.