Abnormalities in the biochemical markers of bone turnover in children withjuvenile chronic arthritis

Objective To study the biochemical markers of bone turnover in children with juvenile chronic arthritis (JCA) and to compare these parameters with those in heal thy children in order to evaluate the relationships between age, disease ac tivity and biochemical variables. Methods Sixty-two children with JCA and 157 healthy children were studied. Serum sa mples were analyzed for their concentrations of minerals, osteocalcin (OC) and bone-specific alkaline phosphatase (BAP). Urine samples were examined t o monitor the excretion of hydroxyproline (HYP) and deoxypyridinoline cross links (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 you nger children from the same population. Lower levels of OC and BAP were obs erved in younger children with JCA (girls less than or equal to 12 yrs.; bo ys less than or equal to 14 yrs.) compared to healthy children of the same age. Older girls with JCA (greater than or equal to 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 ag e-related fashion in JCA. This was demonstrated by a reduction in the marke rs 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 mi d-puberty, while resorption levels increase in children with JCA after this time.