Wet vs. dry chemical analysis of renal stones

Summary  Analysis of renal stones may help in elucidating the pathogenesis of nephro-lithiasis. This study compared the use of 2 methods for the analysis of renal stones. One method is qualitative dry ‘spot tests’ whereas the other is quantitative ‘wet chemistry.’ In the wet chemistry method, dissolved stone material were analysed using automated chemistry analysers, whereas, the dry method involved spot colour end-point detection. Stones (n=64) were analysed by both methods. The majority of stones were calcium oxalate as determined by wet chemistry (57.4 per cent) and spot tests (50.0 per cent). Fewer mixed stones were obtained by the wet chemistry method (16.8 per cent) compared with the spot tests method (39.0 per cent), whereas, more uric acid stones were obtained by the wet chemistry method (5.6 per cent) compared with the spot tests method (1.9 per cent). ‘Pure’ calcium phosphate stones (3.0 per cent) were only obtained by the wet chemistry method. In the wet chemistry method, dissolved stone material did not show significant deterioration on storage for up to 9 days.