Background Juvenile idiopathic arthritis (JIA) is the most common chronic rheumatic disorder of childhood. Beside other complication, it can lead to bone metabolism disturbance and osteoporosis. This bone loss is associated with several factors including low vitamin D. The aim of this study was to determine the prevalence of low bone mineral density (BMD) and hypovitaminosis D in Moroccan patients with juvenile idiopathic arthritis

Methods In this cross-sectional study, Thirty three children with JIA, according to the classification criteria of International League of Associations for Rheumatology (ILAR), were included. The evaluation concerned a Patients underwent anthropometric assessment and clinical evaluation. Serum 25-hydroxyvitamin D2 et D3, other bone markers and BMD were measured. Bone mineral density (in g/cm²) was expressed in Z-scores, the number of standard deviation above or below the mean value of an age- and sex-matched reference population. In children, low BMD was defined as a Z-score less than -2 and osteoporosis was defined as a Z-score less than -2 with a fracture history. Hypovitaminosis D was defined as serum 25-hydroxyvitamin D <30 ng/mL.

Results The median of age of the patients was 11 years [6-14]. Bone mineral density in lumbar spine showed a statistically significant correlation with weight (β=0.613, IC at 95% [0.005-0.013], p=0.001) and age (β=0.5, IC at 95% [0.01-0.044], p=0.003) and the BMD in total body showed a statistically significant correlation only with weight (β=0.33, IC at 95% [0-0.008], p=0.05). There was a positive correlation between 1,25 dihydroxyvitamin D and disease activity (r = -0.52, p=0.03). No relationship was found between vitamin d and BMD and others bone markers.

Conclusions Our study suggests that osteopenia was a frequent complication of JIA and it is associated to a low age and low body mass index (BMI). Its also shows that Vitamin D deficiency is highly prevalent among pediatric patients with JIA and it was associated with important activity of the disease.

Disclosure of Interest None Declared