1 Pediatric Nephrology Unit, Nephrology Center, Santa Casa de Belo Horizonte Hospital, Belo Horizonte, Minas Gerais, Brazil.
2 Pediatric Nephrology Unit, Clinics Hospital, School of Medicine, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
3 Bone and Mineral Disorders Clinic, Division of Pediatric Nephrology, Children's Mercy Hospital and Clinics, University of Missouri at Kansas City, Kansas City, MO, USA. ualon@cmh.edu.