Oral dissolution therapy for radiolucent kidney stones. An old treatment revisited

Abstract

Objective: We present our experience using oral bicarbonate as a dissolution therapy for radiolucent kidney stones in the pre-dual energy CT era. Methods: A retrospective analysis of dissolution therapy was undertaken over a four-year period. Stones were diagnosed as radiolucent on conventional KUB X-ray in combination with either ultrasound or CT KUB. Oral bicarbonate was given at a dose of 2 g tds orally, increased to 2 g five times daily according to urinary pH. Patients monitored their own urine dipstick daily to achieve a pH of at least seven. Results: Altogether 27 patients were identified with radiolucent stones. Stone size varied from 4–40 mm. Average length of therapy was nine weeks. Of the patients, 17 had renal U/S and six had CT KUB as end point imaging. We found that 39% had complete dissolution, 18% had a partial response and 43% showed no response. A high serum uric acid level correlated with a higher incidence of dissolution. Cost-benefit analysis shows bicarbonate therapy to be more cost-effective than lithotripsy, ureteroscopy or nephrolithotomy. Conclusions: Bicarbonate therapy remains an attractive option for the treatment of radiolucent kidney stones. The presence of hyperuricaemia or hyperuricosuria appears to influence the success rate. Further prospective randomised studies are needed to identify the most tolerable and effective treatment regime as well as the optimal duration of treatment. Dual-energy CT may hold the key to identifying patients most likely to benefit from treatment.