Proteinuria is a common laboratory finding, yet kidney biopsies are infrequently performed. During this webinar, we will discuss the diagnostic approach to proteinuria, including when a kidney biopsy should be considered. To help us understand the origin and causes of proteinuria, we will briefly talk about renal physiology. We will then discuss treatment for proteinuria, including how this can change based on the results of kidney biopsies. Finally, we will review some cases in which renal biopsies were performed.