Proteinuria is a common laboratory finding in adolescents. It is often benign and due to transient causes or orthostatic proteinuria. However, it can also be an early sign of underlying conditions that may lead to long-term kidney damage. Early recognition and appropriate diagnostic evaluation are crucial to preventing or slowing disease progression. In this age group, proteinuria may result from newly diagnosed diseases, pre-existing conditions that become clinically evident during adolescence, or previously undiagnosed disorders. Additionally, several proteinuric conditions are specific to this age group, including those related to obesity, recreational drug use, and anabolic androgenic steroids, all of which have increased significantly in recent decades. Adolescence is a transitional phase between childhood and adulthood that presents unique diagnostic challenges due to reduced parental involvement, frequent underreporting of symptoms, and non-compliance with pharmacological treatment or diet. Furthermore, adolescents may receive care in either pediatric or adult settings, where clinical approaches and guidelines often differ. This educational review addresses the diagnostic approach to proteinuria in adolescents and aims to propose a unified algorithm for this age group.