International ring test to check the quality of urolith analyses.

In an international ring test, five mixtures of stone substances were analyzed with different methods in 29 selected stone analysis laboratories in 13 countries. Evaluation revealed very good analysis qualities especially for X-ray diffractometric and infrared techniques. The analytical skills of the investigators are confirmed by a mean standard of quality of 1.69 for all qualitative results determined. It would be possible to improve the diagnosis of urolithiasis by standardizing and centralizing stone analysis.