No single theory of pathogenesis can properly account for human
kidney stones, they are too various and their formation is too complex for simple understanding. Using human tissue biopsies, intraoperative imaging and such physiology data from ten different stone forming groups, we have identified at least three pathways that lead to stones. The first pathway is overgrowth on interstitial
apatite plaque as seen in idiopathic
calcium oxalate stone formers, as well as stone formers with
primary hyperparathyroidism,
ileostomy, and small bowel resection, and in
brushite stone formers. In the second pathway, there are crystal deposits in renal tubules that were seen in all stone forming groups except the idiopathic
calcium oxalate stone formers. The third pathway is free
solution crystallization. Clear examples of this pathway are those patient groups with
cystinuria or
hyperoxaluria associated with bypass surgery for
obesity. Although the final products may be very similar, the ways of creation are so different that in attempting to create animal and cell models of the processes one needs to be careful that the details of the human condition are included.