1. Department of Pediatric Nephrology; Wroclaw Medical University; Wroclaw Poland
2. Department of Nephrology, Kidney Transplantation and Hypertension; Children's Memorial Health Institute; Warsaw Poland
3. Polish-American Children's Hospital, Jagiellonian University; Krakow Poland
4. Clinic of Pediatrics, Nephrology and Endocrinology; Silesian Medical University; Zabrze Poland