Stone Events Research Articles

Surgical Management of Stone Disease in Patients With Primary Hyperoxaluria

To present our experience with surgical management of nephrolithiasis in patients with primary hyperoxaluria (PH). A retrospective chart review from 1994 to 2012 was performed to identify patients with diagnosis of PH. A total of 14 patients with PH were identified with a median follow-up of 18.6 years (range, 0.9-51 years). Median ages at initial symptom and subsequent diagnosis were 6.7 years (range, 1.1-35.5 years) and 0.42 years (range, 0-33.25 years), respectively. Patients underwent a total of 54 procedures at our institution, including ureteroscopy (27 [50%]), percutaneous nephrolithotomy (15 [28%]), shock wave lithotripsy (8 [15%]), and combined procedures (4 [7%]). Overall nonintraparenchymal stone-free rate after the first, second, and third procedures were 59%, 76%, and 78%, respectively. On average, 1.6 procedures (range, 1-4) were required to rid patients of symptomatic stones, which subsequently afforded them a mean of 3.62 years (range, 0.25-21.5 years) without the need for additional intervention. There were 6 Clavien grade ≥III complications in 4 patients, including immediate postoperative end-stage renal disease in 3 patients. Despite optimal medical and surgical management, patients experience recurrent acute stone events requiring multiple urologic interventions. Significant complications such as end-stage renal disease can occur secondary to surgical intervention.

Quantification of asymptomatic kidney stone burden by computed tomography for predicting future symptomatic stone events.

To find the optimal characterization of asymptomatic radiographic stone burden on computed tomography (CT) scans. A survey was sent to stone formers who underwent a CT scan while asymptomatic during a stone clinic evaluation. Symptomatic stone passage events after CT scan were detected by survey and medical record review. Radiographic stone burden was quantified by number of stones, largest stone diameter, automated total stone volume (TSV), and bilateral stones and then compared as predictors of stone events. There were 550 stone formers; 43% had a stone event for a median of 4.7 years after the CT scan. Stone burden by quartiles was 0-1, 2-3, 4-6, and ≥7 for number of stones; 0-2, 3-4, 5-7, and ≥8 mm for largest stone diameter; and 0-8, 9-78, 79-280, and ≥281 mm(3) for TSV; 48% had bilateral stones. The hazard ratios (HRs) for symptomatic event was 1.30 (P <.001) for the number of stones per quartile, 1.26 (P <.001) for largest stone diameter per quartile, 1.38 (P <.001) for TSV per quartile, and 1.80 (P <.001) for bilateral stones. On multivariate analysis, only TSV was an independent predictor of symptomatic events (HR, 1.35 per quartile; P = .01). This risk of events with TSV was also independent of demographics, urine chemistries, and stone composition. Among the 53 patients with interim events between CT scans, a rapid increase in TSV between CT scans (>570 mm(3) per year) predicted subsequent events (HR, 2.8; P = .05). Automated TSV is more predictive of symptomatic events than manual methods for quantifying stone burden on CT scan.

Evaluating kidney stone size in children using the posterior acoustic shadow

Ultrasound, not x-ray, is preferred for imaging kidney stones in children; however, stone size determination is less accurate with ultrasound. In vitro we found stone sizing was improved by measuring the width of the acoustic shadow behind the stone. We sought to determine the prevalence and accuracy of the acoustic shadow in pediatric patients. A retrospective analysis was performed of all initial stone events at a children’s hospital over the last 10 years. Included subjects had a computed tomography (CT) scan and renal ultrasound within 3 months of each other. The width of the stone and acoustic shadow were measured on ultrasound and compared to the stone size as determined by CT. Thirty-seven patients with 49 kidney stones were included. An acoustic shadow was seen in 85% of stones evaluated. Stone width resulted in an average overestimation of 1.2 ± 2.2 mm while shadow width resulted in an underestimation of 0.5 ± 1.7 mm (p < 0.001). A posterior acoustic shadow was seen in the majority of stones and was a more accurate measure of stone size. This would provide valuable information for stone management. [Work supported by NIH DK43881 and DK092197, and NSBRI through NASA NCC 9-58.]

Economic impact of urinary stones.

Kidney stones have been rising in prevalence in the United States and worldwide, and represent a significant cost burden. Cost effectiveness research in this area may enable improvements in treatment efficiency that can benefit patients, providers and the healthcare system. There has been limited research in the cost effectiveness of surgical interventions for stone disease, despite the diverse treatment approaches that are available. Medical expulsive therapy (MET) has been shown to improve rates of stone passage for ureteral stones, and there is evidence that this practice should be liberalized from the standpoint of both clinical and cost effectiveness. While conservative treatment following a primary stone event appears to be cost effective, the economic impact of medical therapy for recurrent stone formers requires clarification despite its clinical efficacy. Future study regarding the cost effectiveness of prevention and interventions for stone disease are likely to improve both the quality and efficiency of care.

Thiazide Diuretic Prophylaxis for Kidney Stones and the Risk of Diabetes Mellitus

Thiazide diuretics used to treat hypertension are associated with a modest risk of diabetes mellitus. It is unknown if there is a similar risk with kidney stone prevention. We identified and validated incident stone formers in Olmsted County, Minnesota from 1984 to 2011 with manual review of medical records using the Rochester Epidemiology Project. The risk of diabetes mellitus after thiazide therapy was evaluated with and without multivariate adjustment for hypertension, age, gender, race, family history of stones, body mass index and number of stone events. Among 2,350 incident stone formers with a median followup of 10 years, 332 (14%) were treated with thiazide diuretics at some point after the first stone event and 84 (3.6%) received the thiazide diuretic only for kidney stone prevention. Stone formers who received thiazide diuretics were more likely to be older, have hypertension, have higher body mass index and have more stone events. The incidence of diabetes mellitus at 10 years after the first stone event was 9.2% in the group that received thiazide diuretics vs 4.2% in those who did not (HR 2.91; 95% CI 2.02, 4.20). After multivariate adjustment the risk of diabetes mellitus was attenuated (HR 1.20; 95% CI 0.78, 1.83). The risk of diabetes mellitus among those receiving thiazide diuretics solely for kidney stones was further attenuated (multivariate adjusted HR 0.80; 95% CI 0.28, 2.23). Thiazide diuretic use for kidney stone prophylaxis was not associated with a high risk of diabetes mellitus. Larger studies are needed to determine if there is a modest risk of diabetes mellitus with thiazide diuretics.

Current practice patterns of urologists providing nutrition recommendations to patients with kidney stones.

To assess urologists' practice patterns and beliefs about dietary therapy for stone prevention. Dietary therapy is offered to stone formers (SFs) by a subset of urologists. While some may involve a registered dietitian (RD) to provide medical nutrition therapy (MNT), most do not as MNT is Medicare-covered only for diabetes and chronic kidney disease. An investigator-created survey was distributed to assess Endourological Society members' opinions, confidence, and practices regarding nutrition therapy. Respondents (n=217) practice largely in academic, hospital/clinic, and private settings. Most (82%) felt dietary therapy should be provided regardless of the number of stone events. Most (90%) said the urologist should provide dietary recommendations and more than half (52%) do so for ≥75% of patients (10% provide it for <25%). Time spent with SFs for nutrition varied from ≤4 to ≥10 minutes (31% and 23%) with 64% feeling this to be insufficient time. Of urologists providing counseling, 58% assess their patients' diets. Self-confidence in determining dietary contributors to risk factors and in quantifying intake of foods/nutrients varied (range 45%-82%). Most (76%) said they would like another provider to give recommendations; 23% partner with an RD to do so. Urologists are interested in dietary stone prevention, despite the fact that the majority have inadequate time to provide it. We identified areas of educational need, specifically, quantifying patients' intake of certain foods/nutrients and identifying whether stone risk factors are diet related. Urologists' skill gaps are precisely the strengths of RDs, and thus, a partnership between RDs and urologists could be beneficial.

Ex Vivo Ureteroscopy with Laser Infundibulotomy in Living Donor Kidney Transplantation

Introduction: The management of incidentally discovered renal stones in living donor candidates is evolving. Recently, the safety and efficacy of ex vivo ureteroscopy for stone removal in donor kidneys have been described.1–3 Here, we present our experience with ex vivo ureteroscopy and laser infundibulotomy for the treatment of a stone contained within a calyceal diverticulum. Calyceal diverticulae are known to harbor bacteria and pose an infection risk for the immunosuppressed recipient,4 leading us to decide that treatment was prudent before transplantation. Materials and Methods: A 38-year-old woman with a previous stone episode presented for the evaluation as a living kidney donor. Preoperative computed tomography angiogram revealed two incidental stones in the left kidney, measuring 6 and 2 mm, with a density of 530 Hounsfield units. Litholink 24-hour urine collection was significant for hypernatremia and hypercalciuria. Following left hand-assisted laparoscopic donor nephrectomy, the kidney was placed on ice and flushed in a standard manner. A flexible ureteroscope was used to visually inspect the collecting system. The 6-mm stone was noted to be within a calyceal diverticulum. Using a 200-μm holmium:YAG laser, infundibulotomy followed by lithotripsy was performed. Stone fragments were removed using a zero-tip nitinol basket. Results: Stone treatment time was 26 minutes. The kidney was visually stone free at the completion of the procedure and was successfully transplanted into a pediatric recipient. Total cold ischemia time was 209 minutes. A modified Lich-Gregoir ureteral anastomosis was performed using a double-J ureteral stent, which was removed 2 weeks postoperatively. Recipient creatinine was 1.2 with no postoperative complications at 2 months of follow-up. Conclusions: Stones contained within a calyceal diverticulum should not serve as an absolute contraindication to kidney donation. Ex vivo stone removal is technically straightforward and has the added benefit of minimizing the risks of bleeding, infection, and anesthetic complications to the donor. Although recipient renal function may have been negatively affected by a 26-minute increase in cold ischemia time, this was likely minimal as successful transplants are routinely performed with cold ischemia times in excess of 10 hours.5 Additionally, this risk is partially outweighed by the benefit of reducing potential complications in the donor by consolidating operative intervention to a single setting. Possible complications of this technique include prolonged operative (and therefore cold ischemia) time, inability to locate the calyceal diverticulum, and postoperative bleeding. Potential candidates for this approach should have a sufficiently small stone burden that can be cleared in a timely manner. Had we not been able to localize the diverticulum, transplantation would have proceeded as planned with consideration of stone removal at a later time. Significant post-transplantation bleeding that did not respond to conservative measures, while unlikely, would be managed on a case-by-case basis. Donors require close urologic follow-up and monitoring of their 24-hour urine parameters to decrease the risk of future stone events. Further research should be performed to evaluate the safety and long-term effects of this technique. Source of work or study: Intraoperative video recorded at the University of Pittsburgh Medical Center. No competing financial interests exist. Running time: 4 mins 25 secs

Editorial Comment

This study highlights that even small residual stone fragments (RFs) after postpercutaneous nephrolithomy (PCNL) are a significant risk factor for subsequent ancillary surgical interventions. In particular, although other groups have demonstrated that RFs >2 mm are associated with stone events, 1 Raman J.D. Bagrodia A. Gupta A. et al. Natural history of residual fragments following percutaneous nephrostolithotomy. J Urol. 2009; 181: 1163-1168 Abstract Full Text Full Text PDF PubMed Scopus (156) Google Scholar these authors highlight that even fragments <2 mm pose a significant risk for repeat procedures with a cumulative retreatment rate of 33.3% over 7 years. Furthermore, the risk of retreatment is greater if RFs are non–calcium based with a cumulative retreatment rate of 56.4%. These data continue to raise the question of whether any RF can be accurately classified as clinically insignificant. Retreatment After Percutaneous Nephrolithotomy in the Computed Tomographic Era: Long-term Follow-upUrologyVol. 84Issue 2PreviewTo examine the long-term retreatment rates and explore prognostic factors after percutaneous nephrolithotomy (PCNL) in the computed tomographic era. Full-Text PDF ReplyUrologyVol. 84Issue 2PreviewWe appreciate the thoughtful comments. Full-Text PDF

Prospective evaluation of 24-hour urine profiles following bariatric surgery in a modern comprehensive care bariatric clinic

To prospectively examine the effect of modern bariatric surgery on 24-hour urine parameters in a comprehensive care bariatric practice (CCBP). 47 consecutive patients in our CCBP underwent serum and 24-hour urine analysis pre-operatively, and 30 returned at 12 months for repeat testing. Paired comparisons for serum metabolite and 24-hour urine measures were performed using a Wilcoxon signed-rank test for continuous variables and McNemar's test for categorical variables. Statistical tests were two-sided, with threshold of significance set at p = 0.05. All 30 patients with pre-operative and 12-month follow-up analysis were free of stone events. 20 (67%) had Roux-en-Y gastric bypass (RYGB), 6 (20%) had laparoscopic gastric banding (LGB), and 4 (13%)h ad laparoscopic sleeve gastrectomy (LSG). 24-hour urinary parameters were available for 27 patients. Median urine oxalate (mmol) was 0.29 pre-operatively and 0.21 at 12 months (p = 0.048). Median urine calcium (mg) was 143 pre-operatively and 180 at 12 months (p = 0.11). Median citrate excretion was 527 pre-operatively and 782 at 12 months (p = 0.22). Median serum creatinine was 0.7 pre-operatively and 0.8 at 12 months (p < 0.001). These trends were preserved with the exclusion of LGB and LSG patients. Modern bariatric surgery (RYGB, LGB, and LSG) as part of a CCBP can still demonstrate alterations of select urinary parameters (particularly oxalate and citrate) in select patients associated with an increased risk of urolithiasis at 1 year follow-up.

MP15-14 CONVERGENT VALIDITY OF A NEW OUTCOME MEASURE FOR PATIENTS WITH UROLITHIASIS: THE WISCONSIN STONE QUALITY OF LIFE SURVEY

You have accessJournal of UrologyGeneral & Epidemiological Trends & Socioeconomics: Quality of Life1 Apr 2014MP15-14 CONVERGENT VALIDITY OF A NEW OUTCOME MEASURE FOR PATIENTS WITH UROLITHIASIS: THE WISCONSIN STONE QUALITY OF LIFE SURVEY Kristina L. Penniston, Rachel Bell, and Stephen Y. Nakada Kristina L. PennistonKristina L. Penniston More articles by this author , Rachel BellRachel Bell More articles by this author , and Stephen Y. NakadaStephen Y. Nakada More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2014.02.567AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES The Wisconsin stone quality of life (WisQOL) questionnaire is the only disease-specific instrument for patients with kidney stones. We previously reported our development and initial validation of the instrument. We tested its convergent validity, a measure of an instrument’s correlation with a similar instrument, against the SF-36 - a widely used, generic health-related QOL survey. METHODS With institutional approval and permission to use the SF-36v2 (Optuminsight Life Sciences, Inc.), we recruited stone formers (SFs) reporting to a clinic visit for evaluation or follow-up. Patients were included if they agreed to complete both the WisQOL and the SF-36 at the visit. RESULTS Participants (n=118; M:F, 69:49; BMI, 30.0±7) were mostly middle-aged, mixed calcium SFs who had undergone prior surgical intervention (age, 53.7±16 y; prior intervention, 75%). Patients varied with respect to stone history (11.7±12 y) and for number of stone events (29% were one-time SFs, 53% had 2-10 prior events, and 18% had >10). Patients were evenly distributed for having or not having stones at the time of the survey (42% each; 24/70% reporting symptoms/no symptoms), while the remainder were unsure if they had stones. The instruments were highly correlated (R=0.56; p<0.0001). Regardless of total score, patients scoring low for items related to pain and vitality on the WisQOL also did so on the SF-36. Of the lowest-scoring patients, most scored lower on the WisQOL than the SF36. The WisQOL, but not the SF-36, captured differences between patients with and without stones at the time of the survey. While only 7 of 36 SF-32 items (19%) were different for patients with and without stones, 89% of WisQOL item scores were different based on patients' stone status. CONCLUSIONS We have previously shown that the WisQOL is sensitive in detecting differences within stone formers (discriminant validity). We now confirm, by testing the WisQOL against a validated "gold standard," that it has convergent validity. Results show excellent general correlation with the SF-36 for total QOL score and for items related to bodily pain and vitality. The SF-36 was less sensitive in detecting symptoms and differences among stone formers than the WisQOL in all other areas. Multi-center trials to continue validity testing are underway. © 2014FiguresReferencesRelatedDetails Volume 191Issue 4SApril 2014Page: e150 Advertisement Copyright & Permissions© 2014MetricsAuthor Information Kristina L. Penniston More articles by this author Rachel Bell More articles by this author Stephen Y. Nakada More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Health-related quality of life (HRQoL) in cystine compared with non-cystine stone formers

Cystinuria is a genetic cause of recurrent kidney stones which may be more recurrent and larger than more common non-cystine stones. They may have a greater impact on health-related quality of life (HRQoL). We measured this impact by surveying HRQoL in patients with stones, comparing non-cystine stone formers (NCSF) to cystine stone formers (CYSF) and both groups to normative values of the US population. We used SF-36v2 via an internet instrument. CYSF patients were recruited via cystinuria-related websites, two patient advocacy groups, and an active endourology practice. NCSF patients were recruited from the same practice and by email. Total n surveyed with scorable data: 214 CYSF and 81 NCSF. The participants included 128 men and 161 women. The group of CYSF were significantly younger (39 vs. 54 years) and suffered longer from kidney stones (255 vs. 136 months). CYSF patients had significantly more episodes of stones than NCSF patients in the last year (N = 108 CYSF, N = 20 NCSF). More frequent stones in the last year and mental comorbidities most often predicted worse scores in the individual HRQoL domains. However, cystine stone composition was a significant predictor of worse scores only for role emotional. Better scores in all SF-36 domains were associated with greater time since the last kidney stone event. Although kidney stones are often transient, kidney stone formers, regardless of stone composition, have a worse HRQoL than the standard US population, which has a normative score of 50, such as general health (41.2 ± 12.8), bodily pain (46.5 ± 11.8) and mental health (45.1 ± 12.6). CYSF are more frequent and severe stone formers compared with NCSF with a resulting greater, direct impact on the HRQoL of CYSF patients. Whether preventive strategies for cystinuria are being properly utilized by practitioners, and which strategies are most effective, should be established.

Stone Disease in Living-Related Renal Donors: Long-Term Outcomes for Transplant Donors and Recipients

Historically, patients wishing to donate their kidney to living related recipients were deemed ineligible if preoperative imaging demonstrated nephrolithiasis. We assess the outcomes of donors with nephrolithiasis and the outcomes of their recipients. Donors undergoing nephrectomy between 2001 and 2011 who had nephrolithiasis on preoperative computed tomography (CT) imaging or a history of stone passage were identified. A retrospective chart review documented donor and recipient demographics, donor 24-hour urine collections, stone size and location, stone events after transplant, and graft function. A seven-question telephone survey regarding development and/or presence of symptomatic nephrolithiasis was conducted. Fifty-four donor-recipient pairs met the inclusion criteria. Twenty-eight (51.9%) patients had valid preoperative 24-hour urine collection, seven (25%) of whom had hypercalciuria. Seven (13%) patients had previous symptomatic nephrolithiasis, but no stones on imaging. Forty-one patients donated a kidney with at least one stone, with a mean stone size of 2.4 mm (range 1-6 mm). Median follow-up for donors and recipients was 22.5 months (interquartile range [IQR] 1-79.3) and 47.4 months (IQR 25.1-76.1), with 50% and 77.7% having a follow-up of more than 2 years, respectively. One donor with nephrolithiasis on preoperative imaging who donated the contralateral kidney passed a stone spontaneously after visiting the emergency department. Otherwise, no other donors or recipients experienced any stone episodes during the follow-up period. The risk of clinical stone recurrence in donors and recipients is low: As such, presence of small caliceal stones should not constitute an exclusion for living-related kidney donation.

Changing Stone Composition Profile of Children With Nephrolithiasis

To determine if this trend toward calcium phosphate stone formation exists in children. This is a retrospective study of medical records of 179 children managed at our medical center from 1992-2010 for whom stone analysis and other pertinent laboratory data were available. A comparison of patients managed from 1992-2000 (P1) and 2001-2010 (P2) was undertaken. Statistical analysis included nonparametric tests. There were no significant differences in the mean age of the 2 cohorts. During both periods, boys comprised a significantly higher proportion during the first decade of life, whereas girls comprised a significantly higher proportion during the second decade. A higher percentage of patients had calcium oxalate (CaOx) stones in P1 compared to P2 (60% vs 47%, P= .0019). There was a significant increase in the percentage of patients having calcium phosphate stones in P2 compared to P1 (27% vs 18.5%, P= .008). Twenty-seven patients had recurrent stones. A comparison of the compositions of the first and last stones of patients within this group demonstrated an increasing proportion of brushite stones (3.7% vs 11.1%, P= .04). Twenty-four hour urine testing results were similar for those with CaOx and calcium phosphate stones. An increasing proportion of children have calcium phosphate calculi. Brushite stones are more prevalent in children with recurrent stone events. The impetus of these shifts is not readily apparent.

Are small residual stone fragments really insignificant in children?

ObjectivesTo assess the significance of asymptomatic residual stone fragments of less than 4mm (clinically insignificant residual fragments [CIRFs]) after shock wave lithotripsy (SWL), percutaneous nephrolithotomy (PNL), and retrograde intrarenal surgery (RIRS) in children. Patients and MethodsEighty-five children were followed up for 6 to 50months (median 22). Outcomes measured were fragment re-growth, stone events (emergency department visits, hospitalization, or additional interventions) and spontaneous fragment passage. ResultsDuring follow-up, 22 children (25.8%) passed residual fragments spontaneously. Highest spontaneous passage rate was found for renal pelvis stones and the lowest for the lower pole stones (57.1% vs. 16.1%; p<0.001). When the number of the fragments increased, the chance of the spontaneous passage decreased (30% vs 20%; p<0.05). Symptomatic episodes including renal colic, hematuria, or urinary tract infection were documented in 34 (40%) patients, and re-growth of fragments was observed in 18 (21.2%). Stone size had no significant effect on spontaneous passage (p=0.079), stone growth (p=0.528), and symptomatic episodes (p=0.402). Twenty-five patients (29.4%) required secondary intervention for stone re-growth or stone related events and the remaining 20 patients (23.5%) needed medical treatment for bothersome symptoms or complications. ConclusionsOur results suggest that 40% of children with CIRFs will become symptomatic and 20% will develop stone re-growth over the following 6months. Only one fifth of the fragments will pass spontaneously without any complications. Therefore, the use of the term “CIRF” is not appropriate for postoperative residual fragments in children.

2260 AN INSTITUTIONAL REVIEW OF ANESTHETIC TIMES FOR URINARY STONES IN PREGNANT WOMEN

INTRODUCTION AND OBJECTIVES: Management options for urolithiasis during pregnancy include trial of passage, temporizing ureteral stent or nephrostomy tube, and definitive treatment with ureteroscopy. Prior research suggests children can suffer adverse long term effects from exposure to medications used for general anesthesia. Specifically, anesthesia exposure greater than two hours or greater than two separate anesthesia exposures prior to the age of four years has been associated with the development of learning disabilities. The goal of this study is to compare the potential anesthesia risk to the fetus when temporizing stents are placed compared to definitive management with ureteroscopy. METHODS: We retrospectively reviewed the records of patients diagnosed with urolithiasis during pregnancy who underwent surgical intervention from 1997 to 2012. Patients were evaluated for a confirmed stone event, defined as a stone visualized on imaging or at surgery, along with management strategy including duration and frequency of anesthetic events. RESULTS: We identified 26 women with urolithiasis during pregnancy who met our inclusion criteria, of which 15 (58%) were managed with stents and 11 (42%) underwent ureteroscopic intervention. In the stent group 6 (40%) required multiple stent exchanges for a mean of 1.47 (range 1-3) anesthetic events and median anesthetic time of 70 minutes (range 29-208 min). Seven (47%) of the women managed with ureteral stent exchange were induced prior to term due to inability to tolerate the stent. Overall the ureteroscopy group had a mean of 1.18 anesthetic events (range 1-2) and 80 minutes (range 37-126 min) of anesthetic exposure. Two (18%) required two procedures either for infection or narrow ureter. None were induced early for pain. Comparing the two groups, there was no significant difference in number of events (p 0.208) or total anesthetic time (p 0.503). CONCLUSIONS: Ureteroscopic intervention appears safe and effective in treating acute stone events with equivalent if not less anesthetic exposure to the fetus compared to temporizing ureteral stents. Furthermore, early induction of labor due to pain is not a concern with ureteroscopy, as it has been shown to be with ureteral stenting. Our study provides further support to the role of definitive stone management instead of temporizing measures during pregnancy.

2244 TOPIRAMATE RESULTS IN A RAPID AND PROGRESSIVE DECLINE IN URINARY CITRATE OVER 60 DAYS: A PROSPECTIVE STUDY

INTRODUCTION AND OBJECTIVES: Topiramate is commonly prescribed for migraine headaches and, recently, weight loss. It exerts a well-known hypocitraturic effect. We characterized the time course to hypocitraturia, a risk factor for calcium lithiasis. METHODS: Under IRB approval, headache clinic providers offered participation to adult patients starting topiramate; a titrated dosage regimen reaching 100-200 mg/d within 1 month was prescribed. Patients withheld initiation until a baseline 24-h urine collection could be done. After starting topiramate, patients provided 24-h urine collections at 30 and 60 d for comparison. RESULTS: Twelve patients (M:F, 0.71; 38 y) were recruited from 9/2011-4/2012 and contributed complete 24-h urine collections, confirmed by 24-h urinary creatinine excretion. At baseline, 83% (n 10) were normocitraturic (urinary citrate 581 274 mg/d); 2 patients were mildly hypocitraturic (250 39 mg/d). At 30 d, mean urinary citrate excretion decreased nearly 300 mg and averaged 279 121 mg/d; it continued to decrease through 60 d (218 82 mg/d), at which time, 83% (6 of 7 patients with 24-h urine analyses) were hypocitraturic (196 64 mg/d for 6 with hypocitraturia). Paired t-tests confirmed differences in urinary citrate between baseline and 30-d and between baseline and 60-d (p 0.01 and 0.002, respectively) but not between 30 and 60 d, though the 22% decline in mean urinary citrate excretion from 30 to 60 d is nonetheless clincally relevant. Urine pH increased from 6.1 at baseline to 6.6 and 6.5 at 30and 60-d, respectively (p 0.04 for each comparison), increasing brushite supersaturation of urine. No patients reported stone events in the 6-12 month evaluation period. Of 8 hypocitraturic patients offered potassium citrate therapy (30 mEq/d), 4 agreed to initiate it. In the 1 patient from this group who has thus far completed a follow-up 24-h urine collection, urinary citrate excretion increased 102 mg/d within 2 weeks. CONCLUSIONS: Hypocitraturia from topiramate is rapid and progressive. This should be taken into account when starting therapy, particularly in patients with a history of urolithiasis or with identifiable lithogenic risk factors. Potassium citrate should be considered as adjunctive therapy in select individuals, and urinary citrate excretion should be monitored to ensure therapeutic effect.

2106 SURGICAL INTERVENTION FOR PRIMARY HYPEROXALURIA: A SINGLE INSTITUTION SERIES

You have accessJournal of UrologyStone Disease: Evaluation & Medical Management (I)1 Apr 20132106 SURGICAL INTERVENTION FOR PRIMARY HYPEROXALURIA: A SINGLE INSTITUTION SERIES Alonso Carrasco, Candace Granberg, and Amy Krambeck Alonso CarrascoAlonso Carrasco Rochester, MN More articles by this author , Candace GranbergCandace Granberg Rochester, MN More articles by this author , and Amy KrambeckAmy Krambeck Rochester, MN More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2013.02.2015AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Primary hyperoxaluria (PH) is an inborn error of glyoxylate metabolism resulting in markedly elevated systemic oxalate levels with subsequent urolithiasis, nephrocalcinosis, and end stage renal disease (ESRD). We present our experience with surgical urolithiasis management in patients with PH. METHODS A retrospective chart review from 1994-2012 was perform to identify patients with diagnosis of PH. RESULTS A total of 149 patients with PH were identified with median follow-up of 11.6 years (range: 0-51). Sixty-five percent were diagnosed before the age 18 years, and 19% presented with ESRD. The rate of PH subtype was 77% type 1, 11% type 2, 10% type 3, and 2% non-1,2,3. Median age at initial symptom and subsequent diagnosis were 5.6 years (range: 0.1-53) and 10.9 years (range: 0-74), respectively. A median delay of 2.7 years (range: 0-62) from first symptom to diagnosis was observed. ESRD developed in 34 (32%) patients at a median time from diagnosis of 15.4 years (range: 0.1-51). A total of 368 urologic surgical interventions for urolithiasis were documented in 68 (46%) patients with an average of 5.84 procedures (range: 1-29) per patient. Procedures included shock wave lithotripsy 152 (47%), ureteroscopy 95 (29%), percutaneous nephrolithotomy 61 (19%), cystoscopy 39 (12%), and open neprolithotomy 16 (5%). Acute stone events occurred at a rate of one every 2.83 years (range: 0-21.5). Patients required an average of 1.36 procedures (range: 1-4) for management of the stone(s), which subsequently afforded a mean of 3.62 years (range: 0.25-21.5) without the need of additional interventions. A total of 9 complications (Clavien grade IIIa-IVa) were observed in 8 patients, which included intervention for retained symptomatic stone in 7 (77%) and development of ESRD in 2 (22%) in the immediate postoperative period secondary to systemic oxalosis crisis. CONCLUSIONS Primary hyperoxaluria is a heterogeneous disease which can pose a significant diagnostic and treatment challenge. Despite optimal medical and surgical management, patients experience recurrent acute stone events requiring multiple urologic interventions. Rendering these patients stone free is not always attainable due to severe parenchymal calcification and it must be recognized that significant complications such as ESRD can occur secondary to surgical intervention. © 2013 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 189Issue 4SApril 2013Page: e863 Advertisement Copyright & Permissions© 2013 by American Urological Association Education and Research, Inc.MetricsAuthor Information Alonso Carrasco Rochester, MN More articles by this author Candace Granberg Rochester, MN More articles by this author Amy Krambeck Rochester, MN More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Editorial Comment

Kidney stone disease is a highly prevalent condition associated with substantial health care cost and patient morbidity. After an initial stone event, the recurrence rate of nephrolithiasis is estimated to be between 35% and 50%. 1 Uribarri J. Oh M.S. Carroll H.J. The first kidney stone. Ann Intern Med. 1989; 111: 1006-1009 Crossref PubMed Scopus (268) Google Scholar The total annual medical expenditures for urolithiasis in the United States were approximately $2.1 billion in 2000. 2 Lotan Y. Economics and cost of care of stone disease. Adv Chronic Kidney Dis. 2009; 16: 5-10 Abstract Full Text Full Text PDF PubMed Scopus (113) Google Scholar One area of potential reduction in morbidity and health care cost is prevention of recurrent nephrolithiasis. Patient-centered Medical Therapy for NephrolithiasisUrologyVol. 81Issue 3PreviewTo elucidate the effect of a patient-centered combined nutritional and medical therapy approach on stone disease management, guided by 24-hour urinary stone risk. Full-Text PDF

Editorial Comment

Urologists are increasingly aware of the need to limit radiation exposure to their patients; however, this can be a challenge when patients expect an accurate and rapid diagnosis. Just as others have shown, these authors report that LDCT scans have sufficient sensitivity to detect stones >2 mm in diameter. This study also demonstrates the preservation of other factors such as stone location, Hounsfield unit density, and SSD in LDCT scans. This additional information, at a cost of about 4-5 mSv more radiation than from a plain abdominal film, makes LDCT appealing for the evaluation of patients with stone formation, even beyond the acute stone event.

Increased Water Intake as a Prevention Strategy for Recurrent Urolithiasis: Major Impact of Compliance on Cost-Effectiveness

We evaluated the economic impact of preventing recurrent stones using a strategy of increased water intake and determined the impact of compliance on cost-effectiveness for the French health care system. A Markov model was constructed to compare costs and outcomes for recurrent kidney stone formers with less than 2 L vs 2 L or more daily fluid intake. Model assumptions included an annual prevalence of 120,000 stone episodes in France, 14.4% annual risk of stone recurrence and a 55% risk reduction in subjects with adequate water intake. Costs were based on resource use as estimated by a panel of experts and official national price lists. Outcomes were from the perspective of the public health payer, and encompassed direct and indirect costs. The total cost of an episode of urolithiasis was estimated at €4,267 including the cost of treatment and complications. This corresponds to an annual budget impact of €88 million for recurrent stones based on 21,000 stone events. Assuming 100% compliance with fluid intake recommendations of 2 L daily, 11,572 new stones might be prevented, resulting in a cost savings of €49 million. Compliance with water intake in only 25% of patients would still result in 2,893 fewer stones and a cost savings of €10 million. Varying the costs of managing stones had a smaller impact on outcomes since in many patients stones do not form. Varying the incidence of complications did not change the incidence of stones and had a negligible effect on overall cost. Preventing recurrent urolithiasis has a significant cost savings potential for a payer as a result of a reduced stone burden. However, compliance is an important factor in determining cost-effectiveness.