Investigations of urinary stone formation following persorption

Persorption is the excretion in urine of particles that have been absorbed (persorbed) from the gastrointestinal tract. In experiments with rats the effect of Herbst was combined with the production of renal calcium oxalate sediments by the oral administration of ethylene glycol and acidification with ammonium chloride. We used this method to investigate whether persorbed corpuscula may represent nuclei of crystallization in the formation of renal calculi. Lead sulfide, zirconium silicate and 45Ca-labeled calcium oxalate crystals were used as persorbable model bodies. It became apparent that orally supplied lead sulfide and zirconium silicate crystals could be found in the urine and the kidneys but they did not function as crystallization centers in the calcium oxalate sediments. However, radioactive labeled calcium could be demonstrated histoautoradiographically within the renal concrements. Our experiments showed that persorbed calcium oxalate crystals can work as nuclei for stone formation.