Percutaneous Nephrolithotomy Can Reduce the Incidence of Sepsis Compared with Flexible Ureteroscopy in Treating Solitary Proximal Ureteral Stone Patients with Positive Urine Culture.

BACKGROUND: Sepsis is a potentially lethal complication for both flexible ureteroscopy (fURS) and percutaneous nephrolithotomy (PCNL). This study is aimed at comparing the sepsis rate after fURS and PCNL and the risk factors for sepsis in patients with solitary proximal ureteral stone. METHODS: We reviewed the data of patients with calculi between 10 mm to 20 mm who underwent fURS or PCNL surgery from Tongji Hospital's database. A total of 910 patients were eligible with 412 fURS cases and 498 PCNL cases. We used univariate analysis and multivariate logistic regression analysis to identify the risk factors for sepsis. Subgroup analysis was performed using logistic regression analysis. RESULTS: In the cohort, 27 (6.6%) and 19 (3.8%) patients developed sepsis after fURS and PCNL, respectively. Multivariate analysis shows that the risk factors for sepsis are fURS (OR = 3.160, P = 0.004), serum WBC ≥ 10,000 cells/µL (OR = 3.490, P = 0.008), albumin - globulin ratio < 1.2 (OR = 2.192, P = 0.029), positive urine culture (OR = 6.145, P < 0.001), and prolonged operation time (OR = 1.010, P = 0.046). Subgroup analysis was conducted using potential risk factors: stone size, serum WBC, urine culture, and albumin-globulin ratio (AGR). In subgroup of positive urine culture, patients were more likely to develop sepsis after fURS than PCNL. CONCLUSIONS: PCNL may be a better choice than fURS to reduce postoperative sepsis, especially for patients with positive urine culture.

Urinary kidney injury molecule-1: a novel biomarker to monitor renal function in patients with unilateral ureteral obstruction.

PURPOSE: This study aimed to investigate the clinical significance of urinary kidney injury molecule-1 (KIM-1) to monitor renal function in patients with obstructive unilateral ureteral calculi. METHODS: Kidneys of 12 male C57BL/6J mice, as well as their urine and plasma specimens, were extracted to detect KIM-1 expressions 24 h after unilateral ureteral obstruction (UUO) construction or sham surgery. Meanwhile, a cohort of 89 patients with unilateral ureteral calculi was retrospectively reviewed. 46 of which received double-J ureteral stent indwelling (group 1) and the remaining 43 were treated conservatively (group 2). Urinary KIM-1 levels in the baseline, 2 h and 1 day after treatments were analyzed. RESULTS: KIM-1 expressions were dramatically higher in mice underwent UUO surgery when compared with the sham group. Clinical data showed urinary KIM-1 levels decreased as time went by for patients in group 1 (1.787 ± 1.081 ng/mL for baseline, 1.668 ± 1.162 ng/mL for 2 h and 0.935 ± 0.526 ng/mL for 1 day after operation; p = 0.0001). Nevertheless, for those in group 2, a mild increase (1.659 ± 0.997 ng/mL, 1.691 ± 0.872 ng/mL and 1.675 ± 0.911 ng/mL, correspondingly; p = 0.9869) was observed. Additionally, a urinary KIM-1 value of 1.04 ng/mL had a sensitivity of 83.1% and specificity of 62.5% to predict the presence of hydronephrosis (95% CI: 0.641-0.873, AUC: 0.757, p < 0.001). CONCLUSIONS: Urinary KIM-1 is a sensitive biomarker of post-renal acute kidney injury (AKI) and might predict the presence of hydronephrosis. It can be used as an effective surrogate to monitor renal function.

Management and outcome of obstructive ureteral stones in the emergency department: Emphasis on urine tests and antibiotics usage.

BACKGROUND: Kidney stone related complaints in the Emergency Department (ED) are common. Current guidelines recommend antibiotic therapy for infected obstructive stones and stone removal in a timely fashion, but there is no clear recommendation for prophylactic antibiotic use for bacteriuria or pyuria in the setting of obstructive ureteral stones. OBJECTIVES: The aim of this study is to evaluate the current management of patients with obstructive ureteral stones in a single ED with emphasis on urine tests and antibiotics use. METHODS: The picture archiving and communication system (PACS) was used to filter the list of patients who received a computed tomography (CT) scan of the abdomen and pelvis that positively identified obstructive ureteral stones. Demographics and clinical data were also recorded and analyzed. RESULTS: Of the patients discharged, 278 patients did not receive antibiotics in the ED or a prescription. Of these, 8 patients had positive culture, 4 patients followed up, and one developed and was treated for a urinary-tract infection. One hundred ninety two patients were not given antibiotics in the ED but received an antibiotics prescription, and 4 patients had positive cultures grow. Two followed up and had no infection-related complications. Fourteen patients were discharged without a prescription after receiving a single dose of antibiotics in the ED, with no positive urine cultures and 9 patients following up without complication. CONCLUSION: Antibiotics were given at the discretion of the provider without clear pattern. A high rate of infectious complication did not occur in the followed up patient group.

Urinary neutrophil gelatinase-associated lipocalin as a biomarker to monitor renal function in patients with obstructive ureteral calculi.

PURPOSE: Our study aimed to investigate the clinical significance of urinary neutrophil gelatinase-associated lipocalin (NGAL) as an effective real-time monitoring biomarker of renal function in patients with obstructive ureteral calculi presenting renal colic. METHODS: A cohort of 89 first-visit patients with renal colic caused by unilateral ureteral calculi were retrospectively reviewed. 46 of which received double-J ureteral stent placement (group 1) and the remaining 43 treated conservatively with analgesics and hydration (group 2) when diagnosed. Urinary NGAL (uNGAL) values in the baseline, 2 h and 1 day after treatments were recorded. The variation of this parameter over time and the association with patients' characteristics were analyzed. RESULTS: uNGAL levels decreased as time went by for patients receiving double-J ureteral stent placement (47.23 ± 28.32 ng/mL for baseline, 40.73 ± 21.86 ng/mL for 2 h and 34.67 ± 18.00 ng/mL for 1 day after operation; p = 0.0363). Nevertheless, for those treating conservatively, the levels emerged a mild increase (50.63 ± 32.30 ng/mL, 56.00 ± 32.01 ng/mL and 60.63 ± 34.08 ng/mL, correspondingly; p = 0.3708). By analyzing the association between uNGAL variation and patients' characteristics of group 1, operation duration showed the best correlation coefficient (Pearson r = 0.6106, r2 = 0.3728, p < 0.0001). CONCLUSIONS: uNGAL can be used as a biomarker to monitor the renal function effectively when serum creatinine (sCr) was within normal limits. And double-J ureteral stent can be considered as a protective factor to renal function in patients with obstructive ureteral calculi presenting renal colic.

Initial collection of an inadequate 24-hour urine sample in children does not predict subsequent inadequate collections.

INTRODUCTION: Approximately half of adult stone formers submit specimens that are either under or over collections as determined by 24-h creatinine/kg. Previously identified predictors of inadequate collection in adults include female sex, older age, higher body mass index (BMI), vitamin D supplementation, and weekday collection. OBJECTIVE: The objective of this study is to determine risk factors for inadequate 24-h urinary specimen collection in the pediatric population. STUDY DESIGN: A retrospective analysis of all children (<18 years of age) with renal and/or ureteral calculi evaluated at the study tertiary care pediatric center from 2005 to 2015 was performed. Those who had at least one 24-h urinary metabolic profile after a clinical visit for kidney and/or ureteral stones were included; children with bladder stones were excluded. Adequate collections had a urine creatinine of 10-15 mg/kg/24 h. A bivariate analysis of potential factors associated with inadequate collection of the initial urinary metabolic profile, including child demographics, parental socio-economic factors, history of stone surgery, and weekday vs. weekend urine collection, was performed. A mixed-effects logistic regression, controlling for correlation of specimens from the same patient, was also performed to determine whether an initial inadequate collection predicted a subsequent inadequate collection. RESULTS: Of 367 patients, 80 had an adequate collection (21.9%): median age, 13 years (interquartile range, 8-16); 61.1% female; 93.5% white; 19.5% obese; and 13.0% overweight. No parental or child factors were associated with inadequate collection (Summary Table). Of inadequate collections, more than 80% were over collections. In the 175 patients with more than one 24-h urinary specimen collection, the effect of an initial inadequate collection on subsequent inadequate collections was not significant after controlling for the correlation of samples from the same patient (p = 0.8). DISCUSSION: Any parental or child factors associated with the collection of inadequate 24-h urine specimens in children were not found. An initial inadequate collection does not predict subsequent inadequate collections. It was surprising that >80% of the inadequate collections were over collections rather than under collections. Possible explanations are that children collected urine samples for longer than the 24-h period or that stone-forming children produce more creatinine per 24-h period than healthy children due to hyperfiltration. CONCLUSION: Inadequate collections are very common, and the risk factors for them are unclear. A repeat collection would be suggested if the first is inadequate. Further studies must be planned to explore barriers to accurate specimen collection using qualitative research methodology.

Early term effect of ureterorenoscopy (URS) on the Kidney: research measuring NGAL, KIM-1, FABP and CYS C levels in urine

ABSTRACT Aim: URS is a very commonly used procedure for treatment of ureter stones. Increased hydrostatic pressure in the collecting system linked to fluids used during the procedure may cause harmful effects on the kidney. The aim of this study is to determine whether the URS procedure has a negative effect on the kidney by investigating NGAL, KIM-1, FABP and Cys C levels in urine. Material and Methods: This study included 30 patients undergoing ureterorenoscopy (URS) for ureter stones. Urine samples were collected 5 times; before the URS procedure (control) and at 1, 3, 5 and 12 hours following the procedure. NGAL, KIM-1, FBAP and Cys C levels were measured in urine and compared with the control values. Results: The NGAL levels in urine before the procedure and at 1, 3, 5 and 12 hours after the procedure were 34.59±35.34; 62.72±142.32; 47.15±104.48; 45.23±163.16 and 44.99±60.79ng/mL, respectively (p=0.001). Similarly, the urinary KIM-1, FABP and Cys C levels were found to increase compared to control values; however this increase did not reach statistical significance (p >0.05). Conclusions: After the URS procedure, there were important changes in NGAL, FABP, KIM-1 and Cys C levels. These changes reached statistical significance for NGAL, but did not reach significance for the other parameters. In conclusion, the URS procedure significantly affects the kidney; however, this effect disappears over time.

Early term effect of ureterorenoscopy (URS) on the Kidney: research measuring NGAL, KIM-1, FABP and CYS C levels in urine.

AIM: URS is a very commonly used procedure for treatment of ureter stones. Increased hydrostatic pressure in the collecting system linked to fluids used during the procedure may cause harmful effects on the kidney. The aim of this study is to determine whether the URS procedure has a negative effect on the kidney by investigating NGAL, KIM-1, FABP and Cys C levels in urine. MATERIAL AND METHODS: This study included 30 patients undergoing ureterorenoscopy (URS) for ureter stones. Urine samples were collected 5 times; before the URS procedure (control) and at 1, 3, 5 and 12 hours following the procedure. NGAL, KIM-1, FBAP and Cys C levels were measured in urine and compared with the control values. RESULTS: The NGAL levels in urine before the procedure and at 1, 3, 5 and 12 hours after the procedure were 34.59±35.34; 62.72±142.32; 47.15±104.48; 45.23±163.16 and 44.99±60.79ng/mL, respectively (p=0.001). Similarly, the urinary KIM-1, FABP and Cys C levels were found to increase compared to control values; however this increase did not reach statistical significance (p >0.05). CONCLUSIONS: After the URS procedure, there were important changes in NGAL, FABP, KIM-1 and Cys C levels. These changes reached statistical significance for NGAL, but did not reach significance for the other parameters. In conclusion, the URS procedure significantly affects the kidney; however, this effect disappears over time.

A Comparison of Urolithiasis in the Presence and Absence of Microscopic Hematuria in the Emergency Department.

INTRODUCTION: Urolithiasis is a common medical condition that accounts for a large number of emergency department (ED) visits each year and contributes significantly to annual healthcare costs. Urinalysis is an important screening test for patients presenting with symptoms suspicious for urolithiasis. At present there is a paucity of medical literature examining the characteristics of ureteral stones in patients who have microscopic hematuria on urinalysis versus those who do not. The purpose of this study was to examine mean ureteral stone size and its relationship to the incidence of clinically significant hydronephrosis in patients with and without microscopic hematuria. METHODS: This is a retrospective chart review of patient visits to a single, tertiary academic medical center ED between July 1, 2008, and August 1, 2013, of patients who underwent non-contrast computed tomography of the abdomen and pelvis and urinalysis. For patient visits meeting inclusion criteria, we compared mean stone size and the rate of moderate-to-severe hydronephrosis found on imaging in patients with and without microscopic hematuria on urinalysis. RESULTS: Out of a total of 2,370 patient visits 393 (16.6%) met inclusion criteria. Of those, 321 (82%) had microscopic hematuria present on urinalysis. Patient visits without microscopic hematuria had a higher rate of moderate-to-severe hydronephrosis (42%), when compared to patients with microscopic hematuria present (25%, p=.005). Mean ureteral stone size among patient visits without microscopic hematuria was 5.7 mm; it was 4.7 mm for those patients with microscopic hematuria (p=.09). For ureteral stones 5 mm or larger, the incidence of moderate-to-severe hydronephrosis was 49%, whereas for ureteral calculi less than 5 mm in size, the incidence of moderate-to-severe hydronephrosis was 14% (p < 0.0001). CONCLUSION: Patients visiting the ED with single-stone ureterolithiasis without microscopic hematuria on urinalysis could be at increased risk of having moderate-to-severe hydronephrosis compared to similar patients presenting with microscopic hematuria on urinalysis. Although the presence of hematuria on urinalysis is a moderately sensitive screening test for urolithiasis, these results suggest patients without hematuria tend to have more clinically significant ureteral calculi, making their detection more important. Clinicians should maintain a high index of suspicion for urolithiasis, even in the absence of hematuria, since ureteral stones in these patients were found to be associated with a higher incidence of obstructive uropathy.

Derivation of decision rules to predict clinically important outcomes in acute flank pain patients.

OBJECTIVE: Routine CT for patients with acute flank pain has not been shown to improve patient outcomes, and it may unnecessarily expose patients to radiation and increased costs. As preliminary steps toward the development of a guideline for selective CT, we sought to determine the prevalence of clinically important outcomes in patients with acute flank pain and derive preliminary decision rules. METHODS: We analyzed data from a randomized trial of CT vs. ultrasonography for patients with acute flank pain from 15 EDs between October 2011 and February 2013. Clinically important outcomes were defined as inpatient admission for ureteral stones and alternative diagnoses. Clinically important stones were defined as stones requiring urologic intervention. We sought to derive highly sensitive decision rules for both outcomes. RESULTS: Of 2759 participants, 236 (8.6%) had a clinically important outcome and 143 (5.2%) had a clinically important stone. A CDR including anemia (hemoglobin <13.2g/dl), WBC count >11000/µl, age>42years, and the absence of CVAT had a sensitivity of 97.9% (95% CI 94.8-99.2%) and specificity of 18.7% (95% 17.2-20.2%) for clinically important outcome. A CDR including hydronephrosis, prior history of stone, and WBC count <8300/µl had a sensitivity of 98.6% (95% CI 94.5-99.7%) and specificity of 26.0% (95% 24.2-27.7%) for clinically important stone. CONCLUSIONS: We determined the prevalence of clinically important outcomes in patients with acute flank pain, and derived preliminary high sensitivity CDRs that predict them. Validation of CDRs with similar test characteristics would require prospective enrollment of 2100 patients.

Factors Associated with Compliance in Submitting 24-Hour Urine Collections in an Underserved Community.

PURPOSE: Patients living in underserved areas do regularly express an interest in stone prevention; however, factors limiting participation, aside from obvious cost considerations, are largely unknown. To better understand factors associated with compliance with submitting 24-hour urine collections, we reviewed our patient experience at the kidney stone clinic at a hospital that provides care for an underserved urban community. MATERIALS AND METHODS: A retrospective chart review of patients treated for kidney and/or ureteral stones between August 2014 and May 2016 was performed. Patient demographics, medical characteristics, stone factors, and compliance data were compiled into our data set. Patients were divided into two groups: those who did and did not submit the requested initial 24-hour urine collection. Analysis of factors related to compliance was performed using univariate analysis and multivariate logistic regression. RESULTS: A total of 193 patients met inclusion criteria for our study, 42.5% (82/193) of whom submitted 24-hour urine samples. Of the 82 collections submitted, 34.1% (28/82) were considered inadequate by creatinine level. A second urine collection within 6 months was obtained in 14.0% (27/193) of patients. Univariate analysis demonstrated that African American (AA) patients were less likely to submit an initial 24-hour urine collection than Caucasian patients (collected: 30.9% vs 51.8%; p < 0.05, respectively). Patients with a family history of kidney stones were more likely to submit an initial 24-hour urine collection than patients without a family history of kidney stones (61.1% vs 38.2%, p < 0.02, respectively). On multivariate analysis, both factors remained significant predictors of compliance with submitting a 24-hour urine collection. CONCLUSIONS: In our underserved patient population, AA patients were half as likely to submit a 24-hour urine collection than Caucasian patients, whereas patients with a positive family history of stones were more than twice as likely to submit than patients with no family history.

[Urolithiasis in the Long-Term GnRH Agonist Treatment of Patients with Paraphilia: 3 Case Studies]. / Urolithiasis bei der Langzeitherapie mit GnRH-Agonisten bei Paraphilien ­ 3 Fallberichte.

The outpatient forensic aftercare department of the Charité Berlin treated 32 paraphilic sex offenders with GnRH analogues within the past 5 years. Out of those patients, three men suffered from urolithiasis and were in need of treatment. All 3 patients had previously developed osteopenia/osteoporosis while on antiandrogen treatment.This article describes these 3 cases and suggests an intense consideration of the possible occurrence of urolithiasis in sex offenders on antiandrogen treatment.

Imaging protocol for suspected ureteric calculi in patients presenting to the emergency department.

AIM: To ensure diagnostic yields were adequate in patients with suspected ureteric calculi with and without haematuria, and to assess whether there was a significant difference between these two groups in men and women. MATERIALS AND METHODS: A retrospective analysis was undertaken of 513 patient records who attended the Emergency Department with suspected ureteric colic over 8 months. RESULTS: 513 patient records were evaluated. The overall positive rate for calculi was 45.4%, with an alternative diagnosis in 14.4%. Of the patients scanned with haematuria 49.36% were positive. The positive scan rate in males was significantly higher than in females (56% v. 31%, p < 0.0001). 32.79% of patients scanned without haematuria had a proven calculus. The positive rate in males without haematuria was 40.39% versus 27.14% in females. CONCLUSION: The overall diagnostic yield of 45.4% is acceptable according to national guidelines. A large number of patients scanned without haematuria were found to have a calculus. This review suggests that in males a negative urine dipstick should not preclude CT investigation for renal colic in the presence of a "classical" history. However, the number of female patients with negative scans suggests that further randomized studies are needed to identify the ideal investigation pathway in women.

Value of Color Doppler ultrasound, kub and urinalysis in diagnosis of renal colic due to ureteral stones.

PURPOSE: Despite the routine use of helical CT in diagnosis of renal colic, there are recent concerns regarding the radiation exposure, overuse and costs. We attempted in this retrospective study to evaluate the accuracy of ultrasound (gray-scale and color Doppler with twinkling), KUB and urinalysis in diagnosis of renal colic due to ureteral calculi presented in Emergency Room. MATERIALS AND METHODS: A total of 939 consecutive cases of renal colic presented to ER have been managed and evaluated by ureteral ultrasound, KUB and urinalysis for the presence of ureteral stones. Non-confirmatory cases were subjected to Helical CT examination. RESULTS: Renal and ureteral ultrasound (gray-scale) alone detected ureteral calculi in 615 cases (65.4%) and after utilizing Color Doppler Ultrasound with twinkling the diagnosis was made with confidence in 935 cases (99.6%) but 4 (0.4%). KUB showed radiopaque stones in 503 (53.6%) patients and no stones were detected in 436 (46.4%). Microhematuria presented in 835 (88.9%) cases while absent in 102 (10.9%). There were 190 (20.3%), 77 (8.2%) and 671 (71.5%) patients with upper, middle and lower ureteral stones respectively. The simultaneous positive findings in US and KUB with microhematuria were found only in 453 (48.2%) cases. CONCLUSIONS: The use of Color Doppler ultrasound with twinkling increased the detection rate of ureteral stones in acute renal colic patients presented to ER with less radiation exposure. Ultrasound examination as a single modality is superior to KUB and urinalysis in initial diagnosis of renal colic.

Value of color doppler ultrasound, kub and urinalysis in diagnosis of renal colic due to ureteral stones

Purpose Despite the routine use of helical CT in diagnosis of renal colic, there are recent concerns regarding the radiation exposure, overuse and costs. We attempted in this retrospective study to evaluate the accuracy of ultrasound (gray-scale and color Doppler with twinkling), KUB and urinalysis in diagnosis of renal colic due to ureteral calculi presented in Emergency Room. Materials and Methods A total of 939 consecutive cases of renal colic presented to ER have been managed and evaluated by ureteral ultrasound, KUB and urinalysis for the presence of ureteral stones. Non-confirmatory cases were subjected to Helical CT examination. Results Renal and ureteral ultrasound (gray-scale) alone detected ureteral calculi in 615 cases (65.4%) and after utilizing Color Doppler Ultrasound with twinkling the diagnosis was made with confidence in 935 cases (99.6%) but 4 (0.4%). KUB showed radiopaque stones in 503 (53.6%) patients and no stones were detected in 436 (46.4%). Microhematuria presented in 835 (88.9%) cases while absent in 102 (10.9%). There were 190 (20.3%), 77 (8.2%) and 671 (71.5%) patients with upper, middle and lower ureteral stones respectively. The simultaneous positive findings in US and KUB with microhematuria were found only in 453 (48.2%) cases. Conclusions The use of Color Doppler ultrasound with twinkling increased the detection rate of ureteral stones in acute renal colic patients presented to ER with less radiation exposure. Ultrasound examination as a single modality is superior to KUB and urinalysis in initial diagnosis of renal colic. .

Assessment of ureterovesical jet dynamics in obstructed ureter by urinary stone with color Doppler and duplex Doppler examinations.

This study was designed to evaluate ureterovesical jet dynamics in obstructed ureter and to compare it with those of contralateral unobstructed side. Forty-six patients with diagnosis of ureteral stone, based on imaging findings in computed tomography were enrolled in this study. The gray-scale ultrasound exam from both kidneys and urinary bladder was performed. Then, ureterovesical jet characteristics including ureteral jet frequency, duration and peak velocity were assessed by color Doppler and duplex Doppler studies in both obstructed and unobstructed ureters by a radiologist, 15-30 min after oral hydration with 750-1,000 mL of water. When compared with contralateral normal side, the ureterovesical jet in obstructed ureter showed less frequency (0.59 vs. 3.04 jets/min; P < 0.05), shorter duration (1.24 vs. 5.26 s; P < 0.05) and lower peak velocity (5.41 vs. 32.09 cm/s; P < 0.05). The cut-off points of 1.5 jets/min, 2.5 s and 19.5 cm/s for difference of ureteral jet frequency, duration and peak velocity between obstructed and contralateral normal ureters yielded sensitivities of 97.8, 95.6 and 100 % and specificities of 87, 87.9 and 97.8 %, respectively for diagnosis of ureteral obstruction. Given the safety of Doppler study and significant differences in flow dynamics of obstructed versus unobstructed ureters, our findings demonstrated the utility of Doppler ultrasound examination as a useful adjunct to gray-scale ultrasound by improving the accuracy of ultrasound exam in diagnosis of ureteral obstruction.

Comparison of secondary signs as shown by unenhanced helical computed tomography in patients with uric acid or calcium ureteral stones.

Unenhanced helical computed tomography (UHCT) has evolved into a well-accepted diagnostic method in patients with suspected ureterolithiasis. UHCT not only shows stones within the lumen of the ureter, it also permits evaluation of the secondary signs associated with ureteral obstruction from stones. However, there we could find no data on how secondary signs might differ in relation to different compositions of ureteral stones. In this study, we compared the degree of secondary signs revealed by UHCT in uric acid stone formers and in patients forming calcium stones. We enrolled 117 patients with ureteral stones who underwent UHCT examination and Fourier transform infra-red analysis of stone samples. Clinical data were collected as follows: age, sex, estimated glomerular filtration rate (eGFR), urine pH, and radiological data on secondary signs apparent on UHCT. The uric acid stone formers had significantly lower urine pH and eGFR in comparison to calcium stone formers, and on UHCT they also had a higher percentage of the secondary signs, including rim sign (78.9% vs. 60.2%), hydroureter (94.7% vs. 89.8%), perirenal stranding (84.2% vs. 59.2%) and kidney density difference (73.7% vs. 50.0%). The radiological difference was statistically significant for perirenal stranding (p=0.041). In conclusion, we found that UHCT scanning reveals secondary signs to be more frequent in patients with uric acid ureteral stones than in patients with calcium stones, a tendency that might result from an acidic urine environment.

Quartz stones: spurious or iatrogenic?

We describe 2 cases of spurious quartz-containing calculi; the first patient-driven and the second iatrogenic. An iatrogenic etiology can occur after the use of holmium:yttrium-aluminum-garnet laser energy because the fiber tip is composed of quartz. To make the diagnosis of a spurious stone, a high degree of suspicion is essential. A quartz stone should prompt the diagnosis of a factitious disorder in the absence of the appropriate surgical history. Psychological counseling and/or referral to a pain management clinic should be considered in such cases.

Clinical association with urinary glycosaminoglycans and urolithiasis.

OBJECTIVES: To determine the clinical association between urinary glycosaminoglycan (GAG) concentration and kidney stone disease. METHODS: Thirty-five patients (14 women and 21 men) with a history of stone disease and 37 controls (13 women and 24 men) were evaluated for urinary GAG concentration. By using a new dye-binding assay, the total GAG concentration in the urine was measured and corrected to urinary creatinine levels (micrograms of GAG per milligram creatinine). RESULTS: The mean urinary GAG concentration in those with stones was significantly lower (31.5 +/- 2.6 microg GAG/mg creatinine) than in the controls (43.8 +/- 3.8 microg GAG/mg creatinine, P = 0.01). Male patients with stones also had a significantly lower mean GAG concentration (26.1 +/- 1.8) than did the female patients (39.6 +/- 5.3, P = 0.009). The mean GAG concentration between ureteral (n = 13) versus renal (n = 22), single (n = 19) versus multiple (n = 16), family history (n = 11) versus no family history (n = 24), large (n = 13) versus small (n = 20), and the presence (n = 22) versus absence (n = 13) of residual stones did not show any significant differences. However, patients with recurrent stone formation (n = 21) had significantly lower mean GAG levels (26.4 +/- 1.6) compared with those with single stone formation (n = 14; 39.2 +/- 5.5, P = 0.01). CONCLUSIONS: Lower urinary GAG levels are more common in patients with stone formation. This may play a more determinant role in male patients and those with recurrent stone formation.

Higher urinary potassium is associated with decreased stone growth after shock wave lithotripsy.

PURPOSE: We correlated serum and urinary biochemical parameters with radiological evidence of stone growth after shock wave lithotripsy. MATERIALS AND METHODS: Biochemical parameters in serum and 24-hour urine collections of 359 patients were correlated with stone growth for 2 years after shock wave lithotripsy. Each patient underwent a minimum of 2 radiological studies at 3 and 12 months and plain abdominal x-ray at 24 months. The presence and size of stones were documented by a radiologist in blinded fashion. Stone growth was defined as measurable growth of a preexisting stone or new stone formation. RESULTS: A total of 209 patients remained stone-free or had no existing stone growth, while stone size decreased in 30. Of the remaining 120 patients with stone growth 72 had new growth and 48 had growth of preexisting stones. Urinary excretion of potassium was significantly higher in those without than with stone growth (mean 24-hour urine collection plus or minus standard deviation 62 +/- 27 versus 54 +/- 23 mmol., p = 0.009). The only parameter significantly associated with stone growth was urinary potassium. Linear regression revealed that for each 10 unit increase in urinary potassium there was a corresponding 2 mm. decrease in stone growth (p = 0.013). CONCLUSIONS: Our results indicate that increased urinary potassium excretion correlates with a decreased risk of stone growth up to 2 years after shock wave lithotripsy, implying that a high potassium diet may be beneficial for preventing stone growth. The effect of potassium supplementation on stone formation and growth must be investigated further.

Identifying stone composition using infrared analysis of filtered urine after ureteroscopic lithotripsy.

BACKGROUND AND PURPOSE: With the development of small-caliber ureteroscopes and lithotripsy devices, it is now possible to perform intracorporeal stone fragmentation without dilatation of the ureteral orifice. Ureteral stones are typically fragmented into small particles that can be difficult to retrieve for stone analysis. Infrared spectroscopy (IRS) of the precipitate from urine after intracorporeal lithotripsy represents a method for obtaining stone analysis. PATIENTS AND METHODS: A total of 69 patients underwent ureteroscopic lithotripsy with the holmium laser or the electrohydraulic probe for stones in the ureter (N = 65) or kidney (N = 4). Each patient's bladder was then drained and the urine filtered. The resulting precipitate was analyzed using IRS. RESULTS: The amount of material for analysis was < or =1 mg in 56 patients (82%). Stone composition was positively identified in 44 patients (64%). Material suitable for analysis was recovered from 73% of patients when the bladder was drained with a cystoscope sheath compared with 43% when a urethral catheter was used (P = 0.03). There was no significant difference in pretreatment stone size in the patients who had a positive v a negative result (11.7 mm v 10.9 mm; P = 0.06). Similarly, the stone location was not significantly related to the likelihood of positive analysis (P = 0.29). CONCLUSION: Straining the urine after ureteroscopic intracorporeal lithotripsy and analyzing the precipitate with IRS is able to identify stone composition in the majority of patients. This method is especially useful in the setting of holmium laser lithotripsy, in which the majority of the stone is converted to spontaneously passable particles.