........................................................................................................................................... 2 INTRODUCTION ............................................................................................................................... 3 METHODS ............................................................................................................................................ 9 Collection of Bile .................................................................................................................................. 9 Selection of Samples .......................................................................................................................... 10 Bile Sample Preparation .................................................................................................................... 12 Analysis ............................................................................................................................................. 14 RESULTS ............................................................................................................................................. 16 DISCUSSION ..................................................................................................................................... 21 Discussion of the Study Design and Methods .................................................................................. 27 Conclusions ....................................................................................................................................... 33 POPULÄRVETENSKAPLIG SAMMANFATTNING ................................................................ 34 REFERENCES ..................................................................................................................................... 35 APPENDIX: TABLES ........................................................................................................................ 39