Juvenile idiopathic arthritis is associated with reduced levels of biochemical bone status indices reflecting altered bone formation

Abstract Introduction Individuals with juvenile idiopathic arthritis (JIA) are at increased risk of impaired bone health and fractures. This prospective case-control study assessed bone mineral density (BMD) and bone and cartilage biomarkers in children with JIA and healthy controls. Methods Fifty-one individuals with well-characterized JIA (age 1.6–17.9 years) and 61 age-matched controls from the same region were included. Joint erosions were assessed radiographically, and BMD was measured by digital X-ray radiogrammetry (DXR). Bone formation was assessed using serum intact procollagen type I N-propeptide (PINP) and bone-specific alkaline phosphatase (BALP), and bone resorption was assessed by C-terminal telopeptide of type I collagen (CTX). Cartilage synthesis was assessed by serum type II procollagen C-terminal propeptide (PIICP). Biomarkers were measured at baseline and 1-year follow-up, while joint erosions were evaluated up to 5 years. Soluble urokinase plasminogen activator receptor (a.k.a. suPAR), rheumatoid factor, anti-cyclic citrullinated peptide antibodies, and antinuclear antibodies were also measured. Results The DXR Z-scores were lower in the polyarticular subtype JIA group in comparison with controls ( p = 0.010). The polyarticular JIA group had lower PINP levels in comparison with controls at inclusion ( p = 0.028) and after 1 year ( p = 0.006). Serum BALP levels were lower in the overall JIA group and in the polyarticular group at 1 year, p = 0.031 and p = 0.042, respectively. Plasma CTX levels were lower in individuals receiving oral steroids compared with those not receiving steroid therapy ( p = 0.006). Higher PIICP levels were found in the oligoarticular subtype JIA group in comparison with the control group ( p = 0.020). Conclusions Based on our findings, children with JIA, particularly those with polyarticular disease, are at increased risk of compromised bone health over time, potentially related to reduced bone formation. These findings underscore the importance of monitoring bone health and implementing targeted interventions to promote optimal peak bone mass acquisition in children with JIA.