· Dilation of renal pelvis due to:
o Obstruction of the pelvo-ureteric junction (often in kids)
o Big prostates
o Kidney stones
· Leads to renal failure due to:
o Chronic interstitial nephritis (as do other things): leucocyte invasion.
o Atrophy of the collecting ducts and distal tubule (which are relatively hypoxic compared to the glomerulus). However, if the tubule goes, the glomeruli scleroses Þ loose whole nephron