The analysis of peculiar urinary (and other) calculi: an endless source ofchallenge

The exact composition of calculi is clinically important, but many specimen s are not examined, with resultant loss of important information. We descri be the incidence and nature of false stones, peculiar calculi and crystals growing on surprising materials. We studied 3100 calculi (97% urinary, 2% d igestive and 1% others). Fourier transform infrared spectroscopy was used t o identify calculi by detailed comparison with libraries of reference spect ra. We also used UV-visible spectroscopy, nuclear magnetic resonance and ga s chromatography-mass spectrometry for specific situations. Among 3100 calc uli, 154 (5%) had an unusual composition; 101 specimens (3.3%) were false c alculi or artifacts, 31 (1%) contained drugs or metabolites and 22 (0.7%) c orresponded to crystallizations around other materials. The findings contri bute to immediate patient management and to advances in scientific and medi cal knowledge. We conclude that the analysis of all calculi must be carried out, to determine their composition, and an efficient strategy must be use d. (C) 1999 Elsevier Science B.V. All rights reserved.