Tertiary Stone Clinic Research Articles

Screening for primary hyperparathyroidism in a tertiary stone clinic, a useful endeavor.

Primary hyperparathyroidism (1HPT) is associated with the risk of developing kidney stones. Our objective was to determine the prevalence of 1HPT amongst SF evaluated at a tertiary stone clinic and determine if it is cost-effective to screen for this condition. We retrospectively reviewed 742 adult SF seen by a single urologic surgeon from 2012 to 2017 all of who were screened for 1HPT with an intact serum PTH (iPTH) and calcium. The diagnosis of 1HPT was based on the presence of hypercalcemia with an inappropriately elevated iPTH or a high normal serum calcium and an inappropriately elevated iPTH. The diagnosis was confirmed by surgical neck exploration. Published cost data and stone recurrence rates were utilized to create a cost-effectiveness decision tree. Fifty-three (7.1%) were diagnosed with 1HPT. 15 (28%) had hypercalcemia and inappropriately elevated iPTH, 38 (72%) had high normal serum calcium levels and inappropriately elevated iPTH. The potential diagnosis was ignored/missed by primary care physicians in 9 (17.0%) based on a review of prior lab results. Cost modeling was undertaken for 5, 10, 15, and 20-year intervals after screening. Based on our prevalence data, historical risks for recurrence and published cost data for stone treatments, cost savings in screening are realized at 10years. These results support screening for primary hyperparathyroidism in patients evaluated in a tertiary referral setting.

Long-Term Adherence to Medications in Secondary Prevention of Urinary Tract Stones.

Purpose: To reduce the high recurrence rate of nephrolithiasis, patients are routinely prescribed secondary chemoprevention therapy with alkali citrate (Alkasolve®; Sam-On Ltd) for uric acid stones and hypocitraturia or hydrochlorthiazide (Disothiazide®; Dexcel Ltd) for hypercalciuria. However, data on adherence to these regimens are limited. The aim of this study was to assess rates of long-term adherence to alkali citrate and hydrochlorothiazide and reasons for nonadherence. Materials and Methods: Patients on follow-up for kidney stone disease at a dedicated tertiary stone clinic, from 2010 to 2016, were asked to complete a telephone survey on adherence to secondary prevention medications and reasons for nonadherence. Compliance was also verified by actual drug distribution as reported through a computerized monitoring system. Results: The cohort included 356 patients with mean age of 58 years, 199 (64% men, 36% women) treated with alkali citrate and 143 (68% men, 32% women) treated with hydrochlorothiazide. Adherence rates were 42% in the alkali citrate group and 52% in the hydrochlorothiazide group (p = 0.05). The main reason for noncompliance in the alkali citrate group (22%) was the number of pills needed to be taken daily. Adverse drug effects were the most common reason for noncompliance in the hydrochlorothiazide group (24%) and in 10% of the alkali citrate group (p < 0.0005). Adherence was poorer in younger patients who did not regularly take other medications than in older patients with other chronic diseases and polypharmacy. Conclusions: About half the patients with clear metabolic abnormalities who were prescribed secondary chemoprevention with hydrochlorothiazide and alkali citrate failed to adhere to the prescribed regimen. Reasons for noncompliance differed between both drugs. The findings of this study may help clinicians to identify patients at risk for nonadherence and suggests potential means to improve compliance rates.

Can a Simplified 12-Hour Nighttime Urine Collection Predict Urinary Stone Risk?

To determine if there is correlation between nighttime 12-hour and traditional 24-hour urine collection in regard to chemistry values and the supersaturations of calcium oxalate, calcium phosphate, and uric acid for the metabolic evaluation of nephrolithiasis. Ninety-five patients were prospectively enrolled from 2013 to 2015. Patients >18 years of age who presented to a tertiary stone clinic and who would normally be counseled for 24-hour urine collection were eligible for the study. Participants completed 24-hour urine collections twice, with each divided into 2 separate 12-hour collections. Day-time collection began after the first morning void and continued for 12 hours. The night collection proceeded for the next 12 hours through the first morning void. Forty-nine 24-hour samples from 35 patients met inclusion criteria and were included in the analysis. Overall, there was strong correlation between the night 12-hour and the 24-hour urine collections with R2 ranging from 0.76 for pH to 0.96 for Citrate. In our analysis of variability, the nighttime 12-hour collection differed from the 24-hour collection by 30% in 1-9 patients (2.0%-18.4%) based on individual chemistry value. Diagnosis of underlying metabolic abnormalities was concordant in 92% of patients. A 12-hour nighttime collection has strong correlation with 24-hour urine collection. As such, simplifying the metabolic evaluation to a 12-hour overnight collection may be feasible-improving compliance and decreasing patient burden.

2081 DOES STONE COMPOSITION CHANGE IN RECURRENT STONE-FORMERS?

You have accessJournal of UrologyStone Disease: Basic Research (I)1 Apr 20132081 DOES STONE COMPOSITION CHANGE IN RECURRENT STONE-FORMERS? Terence Lee, Mohamed Elkoushy, and Sero Andonian Terence LeeTerence Lee Montreal, Canada More articles by this author , Mohamed ElkoushyMohamed Elkoushy Montreal, Canada More articles by this author , and Sero AndonianSero Andonian Montreal, Canada More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2013.02.2500AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES To assess the prevalence of changes in stone composition of recurrent stone-formers. METHODS A retrospective review of 303 patients with confirmed stone analysis presenting to a tertiary stone clinic between July 2009 and June 2012. All stones were analyzed at one centralized laboratory using infrared spectrophotoscopy. Stone type was defined as the predominant stone component of at least 60%. Patients were grouped together according to the first predominant stone type on record. In the mixed stone group, there was no predominant stone composition. Calcium oxalate monohydrate and dihydrate were grouped as calcium oxalate (CaOx). Uric acid (UA) stones included uric acid dihydrate and ammonium urate while calcium phosphate, brushite and struvite were grouped as phosphate (Ph) stones. Patient records including operative reports and imaging studies were reviewed. Patients with multiple stone analyses at least 3 months apart were considered recurrent stone-formers and included in the study. RESULTS The cohort of 303 patients had a mean age of 54.3±30.7 years and 207 (68.3%) were males. The initial stone analysis showed: 145 (47.9%) CaOx, 88 (29%) Ph, 46 (15.2%) UA, 9 (3%) cystine and 15 (5%) mixed. There were 41 (13.5%) recurrent stone-formers with a median time of 404 days. Stone composition changed in 29.3% of recurrent stone-formers. Out of 13 patients with initial CaOx stones, 4 (30.8%) changed to another type (1 mixed, 2 UA, 1 Ph). Out of 11 patients with initial UA stones, 4 (36%) changed to another type (1 mixed and 3 CaOx). Out of 10 patients with initial Ph stones, 1 (10%) changed to CaOx, whereas all 3 patients with mixed stones changed to predominant CaOx, UA and Ph stones (1 patient each). None of the 4 cystinuric patients changed stone composition. CONCLUSIONS Stone composition may significantly change in subsequent stone analysis in recurrent stone-formers. Therefore, stone analysis is recommended on each stone episode. © 2013 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 189Issue 4SApril 2013Page: e854 Advertisement Copyright & Permissions© 2013 by American Urological Association Education and Research, Inc.MetricsAuthor Information Terence Lee Montreal, Canada More articles by this author Mohamed Elkoushy Montreal, Canada More articles by this author Sero Andonian Montreal, Canada More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

65 BONE DENSITY RESULTS OF VITAMIN-D INADEQUATE PATIENTS PRESENTING WITH UROLITHIASIS TO A TERTIARY STONE CENTER

You have accessJournal of UrologyGeneral & Epidemiological Trends & Socioeconomics: Evidence-Based Medicine & Outcomes (II)1 Apr 201365 BONE DENSITY RESULTS OF VITAMIN-D INADEQUATE PATIENTS PRESENTING WITH UROLITHIASIS TO A TERTIARY STONE CENTER Mohamed Elkoushy, Terence Lee, and Sero Andonian Mohamed ElkoushyMohamed Elkoushy Montreal, Canada More articles by this author , Terence LeeTerence Lee Montreal, Canada More articles by this author , and Sero AndonianSero Andonian Montreal, Canada More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2013.02.1443AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Vitamin-D Inadequacy (VDI) and its associated metabolic abnormalities are prevalent in patients presenting with urolithiasis. Vitamin D plays a vital role in bone health and stone-formers are at risk of premature bone loss that may be exaggerated by VDI. Therefore, the aim of the present study was to assess abnormalities in bone density studies for patients with VDI presenting with urolithiasis to a tertiary stone clinic. METHODS A retrospective review of prospectively collected data was performed for patients presenting to stone clinic from November, 2009 to August, 2012. Demographic and clinical data were collected together with metabolic stone work-up and bone density studies. VDI was defined as VD levels < 30 ng/ml. A Dual-energy X-ray Absorptiometry (DXA) scan was used to evaluate the Bone Mineral Density (BMD) at the femoral neck and lumbar spine. The World Health Organization (WHO) criteria were used to define patients with abnormal BMD; normal (within ±1 SD), osteopenia (−1 to −2.5 SD), and osteoporosis (<−2.5 SD). Patients with primary hyperparathyroidism or hypercalcemia were excluded. RESULTS A total of 49 patients with VDI with DXA studies were included; 26 (53.1%) were males. Mean age (95%CI) was 51.5 (42.5-58.3) years, mean BMI (95%CI) was 27.9 (21.6- 31.2) kg/m2 and mean serum VD (95%CI) was 18.4 (16.4-26.2) ng/ml. Twenty-nine patients (59.2%) had abnormal DXA studies where 23 (46.9%) had osteopenia and 6(12.3%) had osteoporosis in the femoral neck and/or lumbar spine. Femoral neck was affected in 42.8% of patients (36.7% osteopenia and 6.1% osteoporosis) while lumbar spine was affected in 40.8% of patients (32.6% osteopenia and 8.2% osteoporosis; one patient had severe osteoporosis with history of osteoporotic fractures). Median serum VD (95%CI) was not significantly different between patients with normal and abnormal DXA scans [19.2 (8-29) vs. 17.2 (6-28) ng/ml, p=0.10). Similarly, median serum VD (95%CI) did not significantly differ between osteopenics and osteoporotics [17.6 (6-28) vs. 15.6 (6.8-23.6) ng/ml, p=0.64]. Of interest, 61.3% of those with abnormal DXA scans were males. CONCLUSIONS A high prevalence of abnormal DXA scans was found in patients presenting with urolithiasis and vitamin D inadequacy. These findings need to be taken into account during evaluation and replacement of vitamin D in this population. © 2013 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 189Issue 4SApril 2013Page: e27 Advertisement Copyright & Permissions© 2013 by American Urological Association Education and Research, Inc.MetricsAuthor Information Mohamed Elkoushy Montreal, Canada More articles by this author Terence Lee Montreal, Canada More articles by this author Sero Andonian Montreal, Canada More articles by this author Expand All Advertisement Advertisement PDF DownloadLoading ...

24-Hour Urine Collection in the Metabolic Evaluation of Stone Formers: Is One Study Adequate?

Abstract Purpose: To determine whether one vs two 24-hour urine collections is optimal in the metabolic evaluation of nephrolithiasis. We retrospectively reviewed all 24-hour urine collections performed at our tertiary stone clinic from July 1997 to February 2012. We identified patients with two 24-hour urine collections performed ≤10 days apart. Samples were analyzed by an outside laboratory for the standard urinary parameters. For each parameter, pairwise t tests were performed and Pearson correlation coefficients were calculated to compare samples 1 and 2. In addition, the number of cases that changed from normal to abnormal or vice versa was also evaluated for each parameter and the Kappa statistic was calculated. A total of 813 subjects submitted two 24-hour urine collections ≤10 days apart. Mean age was 53.2 years, and mean body mass index was 28.8 kg/m(2). Based on creatinine 24/kg, subset analysis was performed for all properly collected samples (n=236). Using pairwise t test, 24-hour urine volume (P=0.0365) and phosphorus (P=0.0387) showed a statistically significant difference between samples 1 and 2. None of the other urinary parameters demonstrated a statistically significant difference when means were compared (pairwise t test, P>0.05), (range 0.061-0.9983). Pearson correlation demonstrated a high degree of correlation between two 24-hour urines for all variables (r=0.66-0.95, each P<0.0001). Depending on the urinary parameter assessed, 5.5% to 44.9% of patients changed from normalcy to abnormality, or vice versa. A single 24-hour urine collection may have changed clinical decision making in up to 45% of patients. Therefore, we recommend two collections to optimize the diagnostic yield and appropriately target stone prevention strategies.

Variations between two 24-hour urine collections in patients presenting to a tertiary stone clinic.

The current Canadian Urological Association (CUA) guideline recommends two 24-hour urine collections in the metabolic evaluation for patients with urolithiasis. The aim of the present study was to compare two consecutive 24-hour urine collections in patients with a history of urolithiasis presenting to a tertiary stone clinic. We retrospectively reviewed 188 patients who had two 24-hour collections upon presentation between January 2010 and December 2010. Samples were collected on consecutive days and examined for the following 11 urinary parameters: volume, creatinine, sodium, calcium, uric acid, citrate, oxalate, potassium, phosphorous, magnesium and urea nitrogen. For each parameter, the absolute value of the difference between the two samples rather than the direct difference was compared with zero. Similarly, the percent difference between samples was calculated for each parameter. The means of the absolute differences between the two samples were significantly different for all 11 urinary parameters (p < 0.0001). The percent differences for all urinary parameters ranged from 20.5% to 34.2%. Furthermore, 17.1% to 47.6% of patients had a change from a value within normal limits to an abnormal value, or vice-versa. Significance was maintained when patients with incomplete or over-collections were excluded. Significant variations among the two 24-hour urine collections were observed in all of the 11 urinary parameters analyzed. This variation may change clinical decision-making in up to 47.6% of patients if only a single 24-hour urine collection is obtained. The present study supports the CUA guideline of performing two 24-hour urine collections.

Prevalence and Metabolic Abnormalities of Vitamin D–inadequate Patients Presenting With Urolithiasis to a Tertiary Stone Clinic

To assess the prevalence and metabolic abnormalities of patients with inadequate vitamin D (VD) presenting with urolithiasis to a tertiary stone clinic in North America. A retrospective review of consecutive patients presenting from August 2009 to January 2010 was performed. Demographic and clinical data were collected together with metabolic stone workup, including 2 24-hour urine collections and serum 25-hydroxy VD [25(OH)D]. VD inadequacy (VDI) included VD deficiency and VD insufficiency defined as 25-(OH) VD levels <20 ng/mL and 21-29 ng/mL, respectively. Of 101 patients, 81 (80.2%) were found to have VDI: 34 (33.7%) were deficient and 47 (46.5%) had insufficient VD. Mean age was 50.4 ± 15.8 years and the mean body mass index was 28.7 ± 5.8 kg/m(2). Forty-two percent were smokers, 51% were recurrent stone formers, and 54% had positive family history of urolithiasis. Hyperparathyroidism was detected in 25.9% of patients, of which 91% of them were secondary to VDI. Hypocalcemia and hyperuricemia were found in 36% and 11% of patients, respectively. Of 81 VDI patients, 69 (85.2%) had complete 24-hour urine collections, of which 92.7% had at least one abnormality. However, only 40% of patients with normal VD had metabolic abnormalities (P <.0001). The most prevalent pattern of urinary abnormalities in VDI patients were suboptimal volume (45%), hypocitaturia (24%), hypocalciuria (33%), hypercalciuria (20%), hyperuricosuria (16%), cystinuria (5%), and hyperoxaluria (7.2%). In this preliminary study, patients presenting with urolithiasis were found to have a high prevalence of inadequate VD associated with abnormalities on metabolic stone work-up.

Effective Radiation Exposure in Evaluation and Follow-up of Patients With Urolithiasis

To quantify the effective radiation dose associated with the evaluation and follow-up of patients with urolithiasis. Retrospective review was performed for consecutive patients presenting to a tertiary stone clinic with acute stone episodes between November 2007 and December 2008, and had at least 2 years of follow-up. Number and modality of imaging studies were collected. Effective radiation exposure (ERE) doses were calculated from the dose length product values reported with each computed tomography (CT) scan. There were 72 males and 32 females with a mean age of 49 years (range 21-78). Patients underwent an average 1.8 (range 0-5) and 0.7 (range 0-2) plain radiographs, 0.82 (range 0-4) and 0.15 (range 0-2) CTs, 0.09 (range 0-1) and 0.03 (range 0-1) intravenous urograms, and 0.3 (range 0-1) and 0.6 (range 0-2) ultrasounds (US) during the first and second years, respectively (all P<.05). The average calculated ERE dose per CT scan was 23.16 mSv (range 4.94-72.77). The calculated mean ERE dose per patient significantly decreased from 29.29 mSv (range 1.7-77.27) in the first year to 8.04 mSv (range 1.4-24.72) in the second year (P<.01). This was because of significantly fewer CT scans and significantly more US imaging during the second year (P<.05). Although 18 (17.3%) patients exceeded 50 mSv during the first year, none exceeded this threshold during the second year. The mean ERE dose did not correlate with stone location, patient age, and sex. The calculated mean ERE dose significantly decreased during the second year of follow-up in patients with urolithiasis because of significantly higher use of US.