This multi-site, pilot study will assess vitamin D supplementation in children and young adults with Glomerular Disease. .

Vitamin D deficiency has been linked to a variety of adverse health outcomes. Nephrotic patients have very low vitamin D levels, and the underlying mechanisms are not known. Furthermore, approaches to safely and effectively supplement vitamin D in these patients have not been established. The purpose of this research study is to learn if vitamin D supplementation is safe and effective in patients with primary glomerular disease and to also help establish the treatment guidelines. About 35 patients with primary glomerular disease, ages 5-30 years old, will take part in this study. Participants will be asked to take vitamin D supplements each day for 12 weeks and will have 3 study visits.