Objectives. Uric acid stones are best managed by chemolysis. Some patients with acutely symptomatic stones opt for endourologic therapies. The radiolucent nature of these stones makes secondary interventions difficult to plan. Computed tomography becomes the modality of choice to identify stone locations and size in these patients. We analyzed patients with uric acid stones referred to our stone center after primary treatment had failed to establish the efficacy of oral alkalinization therapy.

Methods. Eleven patients presented after one or more failed attempts to intervene for uric acid stones. Charts were reviewed for age, sex, time with stone before referral, medical therapies undertaken, number of antecedent urologic interventions, number of radiographic studies performed, subsequent procedures performed, and outcomes with a minimal follow-up of 6 months.

Results. Eight patients were men and four presented with bilateral stone disease (overall, 15 involved upper tracts). Sixty-seven percent of patients had right-sided solitary calculi. All patients at presentation filled out urinary pH diaries. Of the 11 patients, 4 stated they had been prescribed oral alkaline therapy but were found to be noncompliant, 4 were never prescribed this therapy, and 3 took the medication sporadically. All patients were counseled on self-dosing to maintain their urinary pH between 6.0 and 6.5 and to continue the diaries. Computed tomography scans were done in 9 patients, and intravenous urography and ultrasonography in the other 2 patients confirmed the stone burden. Only 3 patients (27%) required subsequent interventions (ureteroscopic laser lithotripsy).

Conclusions. Secondarily referred patients with uric acid stones are best treated with medical therapy. These findings suggest that the initial medical regimens had failed because of noncompliance or lack of effective follow-up by the primary urologist. Seventy-three percent of these patients had dissolution of the stones, requiring no further endourologic intervention.