Is it possible to predict a risk of osteoporosis in patients with juvenile idiopathic arthritis? A study of serum levels of bone turnover markers.

BACKGROUND: Low bone mineral density is a common finding in children with systemic connective tissue diseases, including juvenile idiopathic arthritis (JIA). The influence of the ongoing process of bone remodeling on the disease course merits further investigation. The aim of this study was to assess the clinical relevance of markers of bone turnover and their potential role as predictors of higher fracture risk and, by extension, risk of osteoporosis.

MATERIALS AND METHODS: Blood samples were collected from 59 patients diagnosed with JIA in order to determine serum levels of the following markers of bone turnover: Beta-Crosslaps, osteocalcin, bone alkaline phosphatase, osteoprotegerin and receptor activator for nuclear factor kappa-B ligand. The values were analyzed with laboratory parameters and results of dual X-ray absorptiometry (DXA).

RESULTS: Osteoprotegerin and bone alkaline phosphatase levels were age-dependent. Beta-Crosslaps values were significantly higher in patients with positive JADAS27 score (p=0.0410). Osteoprotegerin levels were higher in patients treated with biological agents than only with disease-modifying anti-rheumatic drugs (p=0.0273). There was no relation between markers of bone turnover and sex, DXA results, dosage of glucocorticosteroids and disease duration.

CONCLUSIONS: The authors postulate performing DXA measurements every 6 months in patients with higher disease activity. The potential lower fracture risk in children with JIA within biological treatment needs further assessment. Age- and sex-adjusted reference rates of bone turnover markers need to be developed for Central European patients in order to assess individual values properly.