The objectives of this study are to assess the
vitamin D status in patients (pts) with inflammatory
joint diseases (IJD), and its correlation with disease activity. 121 consecutive pts (85
rheumatoid arthritis (RA), 22
psoriatic arthritis (PSA), 14
ankylosing spondylitis (AS)) underwent clinical and laboratory evaluation which included kidney and liver function tests, serum
calcium and phosphor levels, 25(
OH)D and
parathyroid hormone (PTH). Disease activity was assessed by
DAS 28 in RA and PSA pts and by BASDAI in AS pts, sedimentation rate (ESR) and CRP. According to activity indexes, pts were divided into subgroups with low (DAS28 < 3.2 and BASDAI < 4), and moderate-to-high disease activity (DAS28 > 3.2 and BASDAI > 4). Associations between serum levels of 25(
OH)D and age, gender, ethnicity, type and disease duration, treatment, (anti-
tumor necrosis factorα (TNFα) agents or DMARDs), seasonal variations, and disease activity were assessed.
Vitamin D deficiency was found in 51 pts (42.1%). The incidence was higher among Arab pts (76.7%) compared to Jews (23%). The difference of 25(
OH)D levels between Arabs (mean 9.4 ± 4.2 ng/ml) and Jews (mean 17.8 ± 8.4 ng/ml) was statistically significant (p < 0.0001). We did not find correlation between
vitamin D levels and the other evaluated factors. A surprisingly high incidence of
vitamin D deficiency was found in IJD patients in a sunny Mediterranean country. This finding justifies the inclusion of
vitamin D in the routine lab work-up of pts with IJD. The only statistical significant correlation was found between
vitamin D level and ethnic origin. Further studies are needed to look for genetic polymorphism of
vitamin D receptors.