Children who have juvenile idiopathic arthritis (JIA) experience smaller gains in bone mass than do healthy children, according to a report in the medical journal Arthritis and Rheumatism. Still, longer follow-up is needed to fully assess the development of the bone-thinning disease Osteoporosis in these patients.

Dr. Gunhild Lien, from Rikshospitalet University Hospital in Oslo, Norway, and colleagues compared bone changes in 108 JIA patients and 108 healthy children and adolescents over a 24-month period. The subjects ranged in age from 6 to 18 years and the average disease duration was 19 months.

Compared with the healthy subjects, JIA patients experienced significantly smaller gains in total body bone mineral content and total body lean mass, the investigators report. Twenty-four percent of JIA patients had low or very low total body bone mineral content compared with just 12 percent of the healthy subjects.

JIA patients also displayed lower levels of bone formation and weight-bearing activities compared with the health subjects, the authors state.

In further analysis, Lien and colleagues found that total body bone mineral content changes could be predicted by the amount of weight-bearing activity and by blood levels of markers indicating bone formation and reduction. In addition, the spread of arthritis to more joints was accompanied by lower total body bone mineral content.

Although awareness of osteoporosis in children with arthritis has improved over the last decade, there is still a need for more studies to investigate the various forms of childhood Osteoporosis, the authors note. The current study suggests that the process that leads to lower bone mass “starts early in the disease course of JIA.”

SOURCE: Arthritis and Rheumatism, March 2005.