1. Department of Urology, VU University Medical Centre, Amsterdam, The Netherlands
2. Department of Clinical Chemistry, VU University Medical Centre, Amsterdam, The Netherlands
3. Department of Urology, Rijnland Hospital, Leiderdorp, The Netherlands
4. Department of Urology, Meander Medical Centre, Amersfoort, The Netherlands
5. Department of Urology, Sint Franciscus Gasthuis, Rotterdam, The Netherlands
6. Department of Endocrinology, VU University Medical Centre, Amsterdam, The Netherlands