Calcification in the renal medulla; a classification based on a prospective study of 2261 necropsies.

Kidneys from 1864 necropsies performed in Brisbane, Australia, and from 397 necropsies performed in Christchurch, New Zealand, were examined macroscopically and microscopically. Three zonal and three focal patterns of renal medullary calcification were defined: (1) Outer medullary cortical calcification seen in hypercalcemic conditions. (2) A band of calcification at the boundary of the inner and outer medullar associated with degenerative changes and correlated with aging and arteriolar disease. (3) Calcification concentrated around the loops of Henle in the papilla, sometimes a striking finding in children and common at all ages. Heavy calcification in this region was injurious to the loops. (4) Fine focal calcification in random distribution throughout the medulla. This lesion was seen in virtually all adult necropsies to some degree. (5) Coarse focal deposits in the papillary region, more common in males and in a hotter climate. (6) Randall's plaques also were common in males and in a hotter climate.