OBJECTIVE: To identify what risk factors on 24-hour urinalysis, if any, predispose patients to have higher percentages of uric acid (UA) stone composition in their stones, with specific emphasis on patients with pure UA stones. METHODS: We retrospectively identified 308 patients from review of a kidney stone analysis database. Patients were grouped according to the percentage UA composition: 10%-20%, 30%-50%, 60%-90%, and 100% UA. Data were extracted from 24-hour urine collections and serum chemistries. Patients taking allopurinol, citrates, or thiazide diuretics were excluded. RESULTS: The percentage UA stone composition increased as patients became older (P = .05) or heavier (P <.001). Gender did not impact the percentage of UA in stones. Although a higher serum UA level was associated with higher UA stone composition (P <.0006), urinary UA levels did not correlate (P = .1). In contrast, urinary pH correlated significantly with higher UA stone composition (P = .03). CONCLUSION: Older and heavier patients with higher serum UA levels are more likely to have a pure UA stone. This information combined with traditional predictors (urine pH, radiopacity of stone, and Hounsfield units) may help identify those most likely to respond to dissolution therapy.
OBJECTIVE: To identify what risk factors on 24-hour urinalysis, if any, predispose patients to have higher percentages of uric acid (UA) stone composition in their stones, with specific emphasis on patients with pure UA stones. METHODS: We retrospectively identified 308 patients from review of a kidney stone analysis database. Patients were grouped according to the percentage UA composition: 10%-20%, 30%-50%, 60%-90%, and 100% UA. Data were extracted from 24-hour urine collections and serum chemistries. Patients taking allopurinol, citrates, or thiazide diuretics were excluded. RESULTS: The percentage UA stone composition increased as patients became older (P = .05) or heavier (P <.001). Gender did not impact the percentage of UA in stones. Although a higher serum UA level was associated with higher UA stone composition (P <.0006), urinary UA levels did not correlate (P = .1). In contrast, urinary pH correlated significantly with higher UA stone composition (P = .03). CONCLUSION: Older and heavier patients with higher serum UA levels are more likely to have a pure UA stone. This information combined with traditional predictors (urine pH, radiopacity of stone, and Hounsfield units) may help identify those most likely to respond to dissolution therapy.
Authors: Tim Nestler; Kai Nestler; Andreas Neisius; Hendrik Isbarn; Christopher Netsch; Stephan Waldeck; Hans U Schmelz; Christian Ruf Journal: World J Urol Date: 2018-08-03 Impact factor: 4.226