A new procedure to evaluate the inhibitory capacity of calcium oxalate crystallization in whole urine.

A procedure to evaluate the global inhibitory capacity of heterogeneous nucleation for a given urine without any modification of its composition was developed. The procedure is based on the use of flat solid substrates that are submerged in urine. The quantification of the amount of formed crystals on the substrate permits to evaluate the crystallization inhibitory capacity for a whole urine. The proposed method was applied to study the inhibitory capacity of urines belonging to stone-formers and healthy people, before and after the ingestion of a dietary complement containing phytate in order to prove its reliability. A clear increase of the inhibitory capacity of the urine was detected in most cases when the dietary complement was consumed. Moreover, lack of crystallization inhibitory capacity was more frequent in stone-formers than in healthy people.