Diagnostic Value of Vitamin D Status and Bone Turnover Markers in Rheumatoid Arthritis Complicated by Osteoporosis

To research the diagnostic performance of clinical potential bone turnover indexes in rheumatoid arthritis (RA) complicated with osteoporosis (OP).

This study involved 87 RA patients, 48 with OP, and 39 without OP, and 204 non-RA control patients, including those with systemic lupus erythematosus, ankylosing spondylitis, primary Sjogren's syndrome, systemic sclerosis, and healthy patients. The levels of 25-hydroxyvitamin D [25(OH)D], β-crosslaps (β-CROSSL), parathyroid hormone (PTH) were measured by electrochemiluminescence (ECLIA), and the level of bone alkaline phosphatase (BALP) was measured by lectin affinity method.

The serum concentration of 25(OH)D in the RA with OP group was significantly lower than the control group (P<0.01), while the levels of β-CROSSL, BALP in the RA with OP group considerably exceeded those found in the control group (P<0.01). The levels of β-CROSSL and PTH were significantly higher in RA patients with OP than without OP (P<0.01), while the level of 25(OH)D was statistically lower than without OP (P<0.01). An unconditional logistical regression analysis proved an association with low 25(OH)D and elevated β-CROSSL in RA with OP, with 25(OH)D demonstrating greatest diagnostic potential according to the ROC curve.

The significantly reduced levels of 25(OH)D and excessive β-CROSSL may indicate a high risk of the secondary osteoporosis in RA patients.