Bone mineral density and turnover in children with systemic juvenile chronic arthritis.

OBJECTIVE: To assess bone mineral status in a group of children with systemic type juvenile chronic arthritis (JCA), which places them at high risk to develop osteoporosis.
METHODS: Bone mineral density (BMD) was measured in 17 children aged 6-18 yrs (mean 14.9 +/- 4.5) with systemic JCA and in 18 matched controls by dual energy x-ray absorptiometry. Bone turnover was determined by quantitative bone scintigraphy, using quantitative single photon emission computed tomography based on skeletal uptake of methylene diphosphonates (MDP uptake). Serum concentrations of minerals, osteocalcin, and bone alkaline phosphatase were determined. Nutrient intake was assessed by a 24 hour dietary recall.
RESULTS: Patients with systemic JCA who received corticosteroid therapy had significantly reduced BMD in both the lumbar spine (p < 0.05) and the femoral neck (p < 0.05) compared to controls, whereas BMD values of the non-steroid systemic JCA patients were not different from controls. Bone turnover measurement by MDP uptake showed no difference between patients with JCA and controls. Levels of calcium, phosphorus, alkaline phosphatase. and osteocalcin were within normal limits in all patients.
CONCLUSION: Patients with systemic JCA receiving longterm steroid treatment may develop a significant decrease in BMD. The normal MDP uptake values together with normal osteocalcin levels that we observed in our patients indicate that their disease is not associated with enhancement of bone turnover rates. These observations might have therapeutic implications for prevention and management of osteoporosis in JCA.