This cross-sectional study will assess bone mineralization with dual energy x-ray absorptiometry (DEXA) in 200 children with a history of Nephrotic Syndrome (NS). Glucocorticoid exposure will be quantitated and correlated with bone mineralization. A multivariate analysis will explore for effect modification and adjust for possible confounding effects of impaired growth and sexual maturation, calcium intake, vitamin D status, physical activity, and cyclosporin therapy. A fracture questionaire will determine the fracture incidence which will be compared with fracture incidence reference data. Review of medical records at CHOP and St. Christopher's Hospital for Children (SCHC) identified 400 eligible children and young adults. To date, 90 children have enrolled, and began participation. Recruitment from the SCHC is just underway. Preliminary results show markedly decreased height and increased weight in the children with NS, consistent with prolonged glucocorticoid therapy. Bone mineral content and bone mineral density is significantly decreased compared to the age-specific reference values provided by the DEXA software. In addition, we are actively recriuting healthy controls to devlop age, gender and race specific reference data. The goal is 200 controls. If the results demonstrate that bone mineralization does not recover with resolution of the NS, or that the fracture incidence is increased, a clinical trial of therapy for optimizing bone mass among children with NS may be indicated.