1 Dialysis Division for Children, Department of Pediatric Nephrology, Public Clinical Hospital No. 1 in Zabrze, ul. 3 Maja 13/15, 41-800, Zabrze, Poland.
2 Chair and Clinical Department of Pediatrics, School of Medicine with the Division of Dentistry in Zabrze, Medical University of Silesia in Katowice, ul. 3 Maja 13/15, 41-800, Zabrze, Poland.
3 Chair and Clinical Department of Pediatrics, School of Medicine with the Division of Dentistry in Zabrze, Medical University of Silesia in Katowice, ul. 3 Maja 13/15, 41-800, Zabrze, Poland. szczep57@poczta.onet.pl.