[Alkalinizing treatment as a preventative of recurrent calcium oxalate lithiasis]. / El tratamiento alcalinizante como preventivo de la litiasis oxalocálcica recidivante.

Alkalinization of urine does not dissolve calcium oxalate but simply inhibits its formation, thus reducing to a high degree the risk of crystallization, precipitation and secondary aggregation. Slight alkalinization is the most effective inhibitor of many recurrent oxalate stones. The solubility of calcium oxalate is always very low and constitutes a different issue of precipitability of oxalate radical as calcium salt which can be satisfactorily influenced by slightly alkalinizing urine. We discuss the reported results of in vitro studies, experiments in animals submitted to oxalate and ethylene glycol overload and the clinical results achieved by alkalinizing treatment of recurrent calcium oxalate stones.

New studies on papillary calculi.

Five hundred spontaneously passed stones were collected during a three-year period in an outpatient clinic. They were studied under a stereoscopical optical microscope. Complementary analyses were performed with infrared spectroscopy, scanning electron microscopy and EDAX. There were 142 true papillary stones (28.4%). The rest (71.6%) showed different non-papillary patterns. Papillary stones, type 1 (61 calculi), had an apatite plaque of intrapapillary origin of which 14 showed calcified tubules. Type 2 showed other substances, presumably due to crystalluria but not to an interstitial papillary process (28 stones). Type 3 showed no plaques in their concave faces (53 stones). In types 1 and 2 whewellite is a secondary growth, the plaque acting as a trigger for the development of calcium oxalate. The possibility of hidden Randall's plaques is discussed. Stones with papillary patterns are not as rare as hitherto considered and merit microscopical study.

Papillary stones: calcified renal tubules in Randall's plaques.

Papillary stones are small, rounded concretions with one smooth convex face and one concave face which corresponds to its implantation on the papilla and in which a whitish Randall's plaque is often present. Eighty-seven papillary stones were studied with stereoscopic, scanning electron microscopic and x-ray dispersive energy analysis. Sixty-three stones had a plaque and 13 of these showed calcified renal tubules that demonstrated their intrapapillary origin and a link between partial papillary nephrocalcinosis and renal stones.