Recurrences of urolithiasis.

A total of 114 patients with urolithiasis were evaluated with particular attention to the number of stone attacks and the stone-free interval between them. Out of the 114 patients, 85 (75%) had a first stone episode. On the other hand, 10 out of 29 patients with recurrent stones had had as many as four or five stone episodes. The stone-free interval between the first and second and the second and third stone averaged nine and seven years, respectively. The ten patients (8%) with four and five stone attacks had an average stone-free interval of only two years. Operations were carried out on 14 of the 114 patients (12%) with 5 of them being operated on earlier twice. There were no significant differences in biochemical values between patients with the second and third, the fourth and fifth stone episodes, although biochemical disturbances were found to be involved in the aetiology of stone formation in each group. Methods of treating urinary stones have developed rapidly in recent years with the use of extracorporeal shock wave lithotripsy (ESWL). In spite of this, an extensive biochemical evaluation is indicated in patients with short stone-free intervals. Patients who are operated on should also be evaluated. Measures to prevent recurrent stone formation can be undertaken on the basis of the aetiology of the stone formation.