Bone turnover is reduced in children with juvenile rheumatoid arthritis

Juvenile Rheumatoid Arthritis (JRA) is frequently associated with osteoporosis. In order to determine if JRA osteoporosis is related to reduced formation or to increased bone resorption or both, serum levels of calcium (Ca), phosphorus (PO4), magnesium (Mg), alkaline phosphatase (ALP), parathormone (PTHi), 25-hydroxyvitamin D3 (25-OHD) and 1,25-dihydroxyvitamin D3 (1,25-(OH)2D), osteocalcin (OT), carboxyterminal propeptide (P-coll-1-c), and carboxyterminal telopeptide of type I collagen (ICTP) were evaluated in 47 JRA children, 33 with active disease and 14 in remission. The therapy consisted of nonsteroidal antiinflammatory (NSAIDs) drugs in pauciarticular subset, NSAIDs and Methotrexate (MTX) in polyarticular, NSAIDs and steroids in systemic onset. OT reflects bone formation, P-coll-1-c reflects collagen production and bone formation, ICTP, marker of collagen degradation in bone, indicates bone destruction. Serum levels of Ca, PO4, Mg, ALP, PTHi 25-OHD and 1,25-(OH)2D were comparable in JRA children and in controls. OT (8.7 +/- 3.7 ng/ml vs 9.6 +/- 5.1), P-coll-1-c (301.2 +/- 118.4 ng/ml vs 264.1 +/- 100.1) and ICTP (15.7 +/- 5.7 ng/ml vs 16.1 +/- 6.1) did not differ statistically in the whole group of JRA children vs controls. OT (8.0 +/- 3.5 vs 10.4 +/- 3.8) and ICTP (14.4 +/- 5.4 vs 18.8 +/- 5.4) were significantly lower in active than inactive group. In polyarticular and systemic onset OT and ICTP were significantly lower than in pauciarticular. No difference was found in active patients treated with steroids vs active patients treated with NSAIDS and NSAIDs plus MTX. The lower serum levels of OT and ICTP in active disease support the hypothesis that both bone formation and resorption are reduced in JRA bone turnover.