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Objective: To determine the effects of calcium supplementation on bone physiology in corticosteroid-free children with juvenile rheumatoid arthritis (JRA) by measuring serum and urinary bone-related hormones, minerals, and markers of bone formation and resorption., Methods: In this double-blind trial, patients were randomized to receive daily oral supplementation with 1,000 mg of calcium and 400 IU of vitamin D or with placebo and 400 IU of vitamin D for 24 months. The effect of calcium supplementation on bone physiology was determined periodically using markers of bone turnover., Results: One hundred ninety-eight patients met the inclusion criteria and were followed up in the study. At baseline, there were no differences in markers of bone turnover between the groups. Patients with < or = 4 joints with active disease had higher serum levels of calcium and parathyroid hormone (PTH). Calcium-treated patients with < or =4 joints with active disease had lower levels of osteocalcin (OC). At followup, levels of 1,25-dihydroxyvitamin D3, PTH, OC, and urine phosphorus were lower in the group receiving calcium supplementation. Hypercalciuria, as determined by the urinary calcium-to-creatinine ratio, was not noted in 24-hour urine studies., Conclusion: Levels of markers of bone physiology were significantly decreased in children with JRA receiving calcium supplementation. The physiologic changes were noted as early as 12 months into calcium supplementation. The hypercalciuria noted on spot testing of the urinary calcium-to-creatinine ratio was not demonstrated on further evaluation, nor did it lead to renal pathology. These findings suggest that the calcium supplementation met physiologic needs and caused an increased calcium loss in urine.

Objective: To study the biochemical markers of bone turnover in children with juvenile chronic arthritis (JCA) and to compare these parameters with those in healthy children in order to evaluate the relationships between age, disease activity and biochemical variables., Methods: Sixty-two children with JCA and 157 healthy children were studied. Serum samples were analyzed for their concentrations of minerals, osteocalcin (OC) and bone-specific alkaline phosphatase (BAP). Urine samples were examined to monitor the excretion of hydroxyproline (HYP) and deoxypyridinoline crosslinks (DPD)., Results: OC, BAP, HYP/Cr, DPD/Cr values were decreased in healthy girls more than 12 years of age and in healthy boys more than 14 years of age compared to younger children from the same population. Lower levels of OC and BAP were observed in younger children with JCA (girls < or = 12 yrs.; boys < or = 14 yrs.) compared to healthy children of the same age. Older girls with JCA (> or = 13 yrs.) were found to have increased HYP/Cr and DPD/Cr values compared to older healthy children., Conclusion: These results indicate that abnormalities of bone metabolism occur in an age-related fashion in JCA. This was demonstrated by a reduction in the markers of bone formation in younger JCA patients. Moreover, in older girls the markers of bone resorption were found to be elevated. Taken together, these findings suggest that bone formation is reduced from early childhood to mid-puberty, while resorption levels increase in children with JCA after this time.