[The incidence distribution and development of a trend of urinary stone substances. An evaluation of the data on over 210,000 urinary stone analyses from the area of the former DDR].

A computer analysis of more than 214,000 urinary stone analysis data recorded in 13 analysis centres in the GDR between 1970 and 1985 was performed. The relative frequencies of urinary stone constituents as pure substances and as main and secondary constituents were determined. Forty-eight percent of all calculi were monomineralic, and the sex ratio (male/female) was 1.96. In the so-called average calculus, mainly whewellite makes up 60.9% of its substance, weddellite 11.8%, uric acid 10.9%, apatite 4.76%, struvite 4.13%, ammonium urate 0.33%, and cystine 0.2%. Artefacts were found in 2.6% of the cases. Trend analysis shows a marked increase in the amount of whewellite and a reduction in the amounts or uric acid, struvite and cystine.