Uromucoids and urinary stone formation.

Crystal formation was studied in fresh urine samples after rapid concentration to standard osmolarity in a rotary evaporator at 37 degrees C. Uromucoids promoted calcium oxalate and calcium phosphate crystal formation and also induced clustering of calcium phosphate precipitates. It is postulated that uromucoid precipitation is the first stage in stone formation. Minerals then deposit on the uromucoid precipitate and the whole complex becomes attached to the renal tubules.