Objectives To determine the factors influencing bone mineral content in patients with juvenile idiopathic arthritis.
Methods A cross sectional studyin patientswith juvenile idiopathic arthritis (JIA) according to the International League of Association of Rheumatology criteria was conducted. Sociodemographic parameters and clinical data related to the disease were collected.
Bone mineral content was measured by dual energy X-ray absorptiometry on Lunar Prodigy machine at the full body. Disease activity of the JIA was assessed by the number of painful joints (PJ), number of swollen joints (SJ), the visual analogic scale (VAS) pain assessed by patient (VASp) and physician (VASd), and biological parameters (ESR,CRP).
Biochemical markers of bone turnover were represented by serum calcium, phosphorus and alkaline phosphatase. Normal serum calcium in children <3 years is 88-110 mg/l and for children>3 years: 90-105 mg/l. For phosphate: 40-60 mg/l. For alkaline phosphatase: 90-450 IU/l.
The daily food intake was assessed by a questionnaire for 7 consecutive days. Two nutritionists analyzed the diet to identify its macronutrient and oligonutriments content. Food intake was analyzed by Bilnut Version 2.01 software 1991.
Results Thirty-three patients with JIA were included. The mean age was10±4.35 years with amale predominance 54.5%. Twenty-four percent had a systemic form, 27% an oligoarticular and 48% a polyarticular form. The median disease duration was 2 years (1 - 4.5). The median duration of taking corticosteroids was 3 years (1-6). The median rate of vitamin D was 20ng/ml (13.85-31.5), for serum calcium 95 mg/l (93-97). The mean rate of phosphorus was 45mg/l ±7.36. The mean rate of alkaline phosphatase was 161UI/l ±52.The median of CMO, PJ, SJ, VASp, VAS d, ESR and CRP were respectively 1044.97g (630-1808), 3 (1-9), 1 (0 - 3), 20 (10-50) 35 (25-50.5) 20 (10.5-40).
There was no correlation between bone mineral content and JIA disease activity parameters: PJ (r =0.06, p=0.77), SJ (r =0.25, p=0.23), VASp (r =0.16, p=0.46), VASd (r =0.02, p=0.91), ESR (r =0.13, p=0.54), CRP (r =0.10, p=0.64).There was no correlation between the bone mineral content and the cumulative duration and corticosteroid dose taken with respectively (r =0.15, p=0.61) (r =0.28, p=0.33).There was a positive correlation between the rate of phosphorus and bone mineral content as well as alkaline phosphatase with respectively (r =0.47, p=0.02) (r =0.41, p=0.04) while the CMO is not correlated with the rate of vitamin D (r =0.14, p=0.5) or the serum calcium levels (r =0.11, p=0.59).
Conclusions This study suggests that bone mineral content was correlated with markers of bone turnover such as alkaline phosphatase and serum phosphate.
Disclosure of Interest None declared
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