Bone mineral content and collagen metabolites in children receiving steroid treatment for nephrotic syndrome

Bone mineral density (BMD) and content (BMC) were measured in nine children treated with corticosteroids for nephrotic syndrome and in age-matched controls, using dual-energy X-ray absorptiometry (DEXA). The urinary excretion of cross-linked N-telopeptide (NTx) released from collagen type I as a specific marker of bone resorption was also measured. There were no significant differences in body size, BMD results or NTx urinary concentrations between patients and controls, nor could any significant differences be found when the six patients given a cumulative corticosteroid dose of >15 g were analysed separately. The lack of significant differences could be due to the small number of patients included in the study. But when the measured BMD and BMC were analysed according to methods that corrected for body size and puberty stage, values well within the normal range were found in patients as well as in controls. There was, however, a significant, negative correlation between the urinary excretion of NTx and the cumulative dose of corticosteroids. CONCLUSION: Despite treatment for long periods with high, cumulative doses of corticosteroids, the skeletons of the patients had a normal mineral content, which is encouraging for all those in need of steroids for nephrotic syndrome. A negative correlation between urinary collagen degradation products and the cumulative steroid dose might point to a reduced growth velocity in patients on high doses of steroids earlier than an effect on bone mineralization.