Use of the Discriminant Index in Dynamic Treatment to Reduce Recurrence of Calcium Oxalate Kidney Stones

Summary— Treatment with phosphates, thiazides and allopurinol was undertaken in 54 idiopathic calcium oxalate stone formers, 38 of whom were recurrent stone formers. The patients were followed up for 1 1/2 to 4 years (mean 2.6). During the same period at the pre‐treatment stage the patients formed 80 stones, but during therapy only one stone was formed. A dynamic scheme of therapy was used. Each patient was tested before the start of drug treatment by the discriminant index (DI) method, which measures the overall inhibitory potential to calcium oxalate crystallisation. About 10 days after the start of treatment the DI was tested again. If the response was positive, therapy was continued; if not, the patient was given another drug. Adjustments were made as required. The stopping of stone formation correlated well with the DI prediction but less well with the hypocalciuric effect of the drugs.