1. Department of Internal Diseases, Nephrology and Dialysis, Military Institute of Medicine-National Research Institute, 04-141 Warsaw, Poland
2. Department of Epidemiology and Biostatistics, Institute of Mother and Child, 01-211 Warsaw, Poland
3. Department of Internal Diseases and Endocrinology, Medical University of Warsaw, 02-097 Warsaw, Poland
4. Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA