Evaluating the role of serum sclerostin as an indicator of activity and damage in Egyptian patients with rheumatoid arthritis: university hospital experience.

Objective: Sclerostin is an osteocyte-derived glycoprotein which inhibits the canonical Wnt pathway essential for osteoblastic activity decreasing bone formation. Its potential role in rheumatoid arthritis (RA) pathogenesis was highlighted by experimental studies. Here we measured the serum sclerostin in RA patients and evaluated its relationship with disease activity and damage.

Methods: One hundred RA patients and 80 age and sex-matched healthy controls were enrolled in the study. Bone biomarkers were evaluated for all participants including total calcium, phosphorus, alkaline phosphatase, 25-hydroxy vitamin D, and intact parathyroid hormone, in addition to fibroblast growth factor-23 (FGF23) and serum sclerostin. For RA patients, carotid intima-media thickness, brachial artery flow dilatation, and musculoskeletal ultrasonography using ultrasonography-7 joint score were done, and DAS28-ESR was calculated.

Results: Median serum sclerostin in our patients was 186.5 ± 22.7 pg/ml which was significantly higher than in controls 60.6 ± 7.1 pg/ml (p < 0.002). Serum sclerostin showed no correlation with disease activity, bone erosions, carotid intima-media thickness, brachial flow dilatation, and the examined bone biomarkers. However, it had a strong correlation with FGF23 (r coefficient 0.988, p < 0.000).

Conclusion: Although serum sclerostin was elevated in RA patients, it could not be used as a prognostic marker for disease activity, bone erosions or atherosclerosis.Key Points• Serum sclerostin may not reflect changes in the joint microenvironment being not correlated with ultrasonography-detected synovitis or erosions.• Serum sclerostin was elevated in RA patients irrespective to their age or gender.• The positive correlation with FGF23 may provide evidence for sclerostin contribution in bone demineralization in RA patients.