Kidney stones made of proteins are infrequent. Typically, these types of stones are encountered in three primary clinical contexts:
Chronic Pyelonephritis may result in the formation of soft matrices spreading into all kidney cavities, pylons, and calyces. The typical morphology of such soft stones is type VIa. These stones are light brown in color in contrast to other types of protein-rich stones.
Stones produced by individuals with heavy Proteinuria and/or hematuria are classified as Type VIb kidney stones. Type VIb stones are made of loose concentric protein sheets often covered by crystals from metabolic, infectious, or drug-related origin. The color and structure of these stones are influenced by the compounds deposited on the protein sheets.
Protein stones (or more often) mixed protein and calcium oxalate stones may be found in individuals at end-stage renal disease (ESRD) and are treated for several months or years by maintenance dialysis. These stones are commonly small in size (1-3mm) and are referred to as Type IVc stones. Internally, Type IVc stones are made of unorganized light groupings (agglomerates) of whewellite and proteins surrounded by a dark brown shell often composed of nearly pure proteins. These stones result from moderate hyperoxalemia (excess oxalate in the blood), defective reabsorption of small proteins in the proximal tubule, and supplementation with calcium and Vitamin D. It is a rare side effect of the long-term management of ESRD patients .