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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 investigate the frequency of hypercalciuria and the relationship between hypercalciuria and hematuria in patients with juvenile rheumatoid arthritis (JRA)., Methods: Twenty-eight children with JRA were studied, as well as 10 patients with acute arthritis unrelated to JRA and 14 healthy children as control groups. Cases with urinary calcium excretion (UCE) >4 mg/kg/day were considered hypercalciuric. Urinalysis was performed for detecting hematuria in all cases., Results: UCE was 4.19 +/- 2.9 mg/kg/day in patients with JRA, 1.94 +/- 1.57 mg/kg/day in children with acute arthritis, and 2.0 +/- 1.45 mg/kg/day in healthy children. UCE was significantly higher in JRA compared with the other study groups. Of the 28 patients with JRA, 13 (46.4%) had hypercalciuria and 6 (21.4%) had hematuria. UCE was significantly higher in hematuric patients with JRA than in those with no hematuria (p<0.05). UCE in patients with JRA without hematuria was also higher than the UCE values detected in the disease and healthy control groups (p<0.05)., Conclusion: Hypercalciuria is a frequent finding in patients with JRA [13/28 (46.4%)] and should be considered during the investigation of hematuria in patients with JRA.

Demineralization of bone is a frequent finding in children with juvenile chronic arthritis (JCA). Recently there have been reports about hypercalciuria accompanying JCA. This is believed to be associated with increased bone resorption due to cytokines and immobility of the patients and steroid treatment. In 12 patients with confirmed diagnosis of JCA basic biochemical indices of bone metabolism, were performed (S-Ca, P, ALP, U-Ca/U-creatinine, U-P). Bone mineral density (BMD) was measured using DPXA method and results obtained were compared to the Lunar BMD DPXA standards. In spite of decreased BMD, no significant hypercalciuria was found and other mentioned biochemical indices of bone and mineral metabolism were normal as well.