Division of Nephrology, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, and

Department of Pediatrics, Perelman School of Medicine of the University of Pennsylvania, Philadelphia, Pennsylvania

Correspondence: Dr. Erum A. Hartung, Children's Hospital of Philadelphia, 3500 Civic Center Boulevard, Philadelphia, PA 19107. Email: [email protected]

See related article, “Tolvaptan for Children and Adolescents with Autosomal Dominant Polycystic Kidney Disease: Randomized Controlled Trial,” on pages 36–46.