Treatment of calcinosis in juvenile dermatomyositis with probenecid: the role of phosphorus metabolism in the development of calcifications

Objective. To report the efficacy of probenecid for calcinosis of juvenile dermatomyositis (JDM) and assess the changes in phosphorus metabolism durin g treatment. Methods. Biochemical studies of calcium and phosphorus metabolism were perf ormed in a 9-year-old girl with JDM and extensive calcifications before and during probenecid treatment. Results. The calcifications resolved over 18 months of treatment, Probeneci d was found to be effective in reducing calcifications by increasing renal phosphate clearance. Conclusions. The tendency for calcifications in some patients with JDM migh t be related to an increase in renal phosphate reclamation, and therefore; probenecid treatment may be effective in these patients.