Increased likelihood of detecting kidney stone risk factors with multiple 24-hour urine collections

Among calcium kidney stones formers, the number of urinary risk factor abnormalities that are identified increases with the number of 24-hour urine collections and with collections obtained at later time points after the occurrence of a stone. In this study of 75 recurrent idiopathic calcium kidney stone formers, the relative diagnostic utility of one (U1), two (U2), and three (U3) urine collections, as well as variations in timing of collections after a clinically evident stone event, was evaluated. U1, U2, and U3 were obtained at a mean period of 105, 116, and 163 days after the stone event, respectively. The largest number of abnormalities were observed with the performance of 3 urinary collections (U1+2+3).