Crystalline composition of urinary stones in Norwegian patients

During a 5 year period, 500 stones from the upper urinary tract and 100 from the urinary bladder of as many unselected and consecutive patients were obtained in one hospital and analysed crystallographically. 90.4% of the upper urinary tract stones and 65% of the bladder stones belonged to the groups of calcium stones, while 6.6% and 24%, respectively, were triple phosphate stones. The contribution of calcium stones to this material is higher and that of triple phosphate stones lower than in comparable materials. Frequency variations between materials also exist within the groups of calcium stones, and for uric acid, urate and cystine stones. On the basis of published material, it is not possible to say if these differences are renal or reflect variations in the selection of stones and the methods of analysis. Reports on stone materials should include information on these aspects in order to allow meaningful comparison. Distinction between stones from the upper urinary tract and from the bladder is mandatory. The composition pattern reported here is believed to be as representative as is possible to obtain. A major part of stones from the upper urinary tract is, however, lost for analysis following spontaneous passage. Such stones are more often pure calcium oxalate and less often triple phosphate stones than those which are obtained by surgical methods, and the extent to which they are obtained will influence the findings in stone materials.