Significance of densitometry and biochemical tests in diagnosis of osteoporosis in children suffering from juvenile rheumatoid arthritis
Danuta Chlebna-Sokół, Henryka Brózik, Tadeusz Bujnowski, Małgorzata Biernacka, Elżbieta Loba-Jakubowska, Anna Sikora, Elżbieta Smolewska
Med Sci Monit 1999; 5(4): CR720-725
Available online: 1999-07-01
Background:The aim of this study was to evaluate the role of different tests in the diagnosis of osteoporosis, in children suffering from juvenile rheumatoid arthritis (JRA), as well as to assess the correlation between test results and clinical disease symptoms.
Material/Methods:Tests were performed in 30 children aged between 5-18 years (24 girls, 6 boys), suffering from juvenile rheumatoid arthritis. We evaluated the bone mineral density (BMD - g/cm2, Z-score) by means of dual energy X-ray absorptiometry (DEXA method) using the 'total body' program in all children and in some by means of the lumbar vertebral column using the 'spine' program. Moreover, we also determined the serum calcium, phosphorus and magnesium levels, as well as the urine excretion of these ions and that of total hydroxyproline. We measured the activity of alkaline phosphatase and its bone isoenzyme, as well as 25-hydroxyvitamin D and parathyroid hormone levels.
Results:Based on bone densitometry results osteoporosis was diagnosed in 12 of the patients with JRA (40%). These children demonstrated clinical and radiological manifestations of osteoporosis. Distinct biochemical test abnormalities included decreased parathyroid hormone, 25-hydroxycholecalciferol vitamin D and magnesium blood concentrations and increased hydroxyproline excretion with urine. Such abnormalities also appeared in children with JRA but without osteoporosis, although less frequently. The longer the disease had lasted the lower the bone mineral density.
Conclusions:Densitometry should be considered as the most important and objective method of diagnosing osteoporosis in children with JRA. Urine hydroxyproline excretion seems to be of great practical significance amongst biochemical indices.
Keywords: densitomery, Diagnosis, Osteoporosis