Initiation and growth of uroliths

The urinary concentrating capacity of terrestrial animals often results in a high degree of urinary supersaturation. Supersaturation provides a driving force for rapid precipitation of solids. For some minerals in urine, the balance between supersaturation and presence of inhibitors determines whether crystal growth will occur. If crystals are delayed in their transit through the urinary tract, they may grow to such a size that they cannot readily pass through the ureters or urethra.