Do Urinary Cystine Parameters Predict Clinical Stone Activity?

PURPOSE: An accurate urinary predictor of stone recurrence would be clinically advantageous for patients with cystinuria. A proprietary assay (Litholink, Chicago, Illinois) measures cystine capacity as a potentially more reliable estimate of stone forming propensity. The recommended capacity level to prevent stone formation, which is greater than 150 mg/l, has not been directly correlated with clinical stone activity. We investigated the relationship between urinary cystine parameters and clinical stone activity. MATERIALS AND METHODS: We prospectively followed 48 patients with cystinuria using 24-hour urine collections and serial imaging, and recorded stone activity. We compared cystine urinary parameters at times of stone activity with those obtained during periods of stone quiescence. We then performed correlation and ROC analysis to evaluate the performance of cystine parameters to predict stone activity. RESULTS: During a median followup of 70.6 months (range 2.2 to 274.6) 85 stone events occurred which could be linked to a recent urine collection. Cystine capacity was significantly greater for quiescent urine than for stone event urine (mean ± SD 48 ± 107 vs -38 ± 163 mg/l, p <0.001). Cystine capacity significantly correlated inversely with stone activity (r = -0.29, p <0.001). Capacity also correlated highly negatively with supersaturation (r = -0.88, p <0.001) and concentration (r = -0.87, p <0.001). Using the suggested cutoff of greater than 150 mg/l had only 8.0% sensitivity to predict stone quiescence. Decreasing the cutoff to 90 mg/l or greater improved sensitivity to 25.2% while maintaining specificity at 90.9%. CONCLUSIONS: Our results suggest that the target for capacity should be lower than previously advised.

Convective radiofrequency water vapor thermal therapy for benign prostatic hyperplasia: a single office experience.

BACKGROUND: Convective radiofrequency water vapor thermal therapy with the Rezum system is a relatively new treatment for benign prostatic hyperplasia (BPH). We present results from a single surgeon in an office setting. METHODS: A retrospective review of 129 patients from a single surgeon who underwent the Rezum procedure was performed. All patients were at least 4 months out from treatment. International prostate symptom scores (IPSS), maximum flow rates (Qmax), residual urine volumes, medication usage, and adverse events were monitored. Data were analyzed at baseline, 15-45 days, 46-90 days, and 91-180 days after treatment. A scripted patient questionnaire was attempted over the phone to all patients. It was administered by a resident and medical student who do not work in the provider's office. RESULTS: Maximal effects were noted at the 91-180 day interval. IPSS improved from a baseline of 18.3 to 6.9 and Qmax from 10.5 to 16.8 mL/s. Improvements were independent of starting symptom score, median lobe treatment, and prostate size. There was a 17% prostate volume reduction based on TRUS and 14% based on PSA. The most common adverse events were urinary tract infections (17%) and transient urinary retention (14%). In total 90% of patients were able to come off their BPH medications and 86% of patients would recommend the procedure to a friend. CONCLUSIONS: Rezum radiofrequency water vapor thermal therapy offers a minimally invasive option for BPH management with moderate improvement in symptoms and flow rate. The results appear to be independent of prostate size or presence of a median lobe, and have now been replicated in a single office setting.