Profile of the brushite stone former

Abstract

Purpose: The incidence of brushite stones has increased during the last 3 decades and we report our experience with brushite stone formers.

Materials and methods: From 1996 to 2008 we identified 82 patients with brushite urinary calculi. After institutional review board approval a review of our prospectively collected database was performed.

Results: There were 54 (65.9%) male and 28 (34.1%) female stone formers. Mean age was 44 years (range 4 to 84). Prior stone events were reported by 69 (84.1%) patients with 54 (78.3%) having received shock wave lithotripsy. Bilateral calculi were present in 28 (34.1%) patients. Mean stone area was 29.2 mm(2) (range 2 to 130). Surgery was performed in 80 patients including 63 (76.8%) percutaneous nephrolithotomy, 8 (9.8%) ureteroscopy, 3 (3.7%) shock wave lithotripsy, and 6 (7.3%) ureteroscopy and percutaneous nephrolithotomy. After primary and secondary procedures 76 (92.7%) patients were rendered stone-free. Metabolic urine studies were available in 45 patients. All patients demonstrated 1 or more abnormalities, with hypercalciuria (greater than 250 mg daily for women and greater than 275 mg daily for men) in 38 (80.9%), urine pH greater than 6.2 in 29 (61.7%), urine volume less than 2 l in 27 (57.4%), hypocitraturia (less than 320 mg daily) in 22 (46.8%), hyperuricosuria (greater than 750 mg daily in women, greater than 800 mg daily in men) in 8 (17%) and hyperoxaluria (greater than 32 mg daily in women and greater than 43 mg daily in men) in 5 (10.6%). Recurrent stone events occurred in 31 (37.8%) patients at a mean of 33 (range 2 to 118) months from treatment.

Conclusions: Brushite stone formers are a treatment challenge. Almost a third will present with bilateral stones and the stone burden is sizeable. Nearly 80% of patients report having prior shock wave lithotripsy and recurrent stone events occurred approximately 3 years after treatment. All patients with brushite stones in this cohort had an underlying metabolic abnormality and specifically brushite stones should be heralded as a marker for hypercalciuria. Based on these data we recommend all brushite stone formers undergo 24-hour urine studies and have close long-term followup.