History Of Urolithiasis Research Articles

An Unusual Cause of Abdominal Pain: Thiazide-Related Hypercalcemia in a Patient with Veiled Hyperparathyroidism and Thyroid Papillary Carcinoma

Hypercalcemia is an uncommon cause of abdominal pain and may be overlooked in the Emergency Department. In this case report, we describe the case of a 48-year-old woman with a prior history of urolithiasis who presented to the Emergency Department with diffuse abdominal pain. She had taken Trichlormethiazide 1 mg daily for her urolithiasis. She was diagnosed with thiazide-related hypercalcemia; hyperparathyroidism and thyroid papillary carcinoma were unveiled during her hospitalization. A thorough history and complete physical examination, paired with appropriate but judicious diagnostic testing, are essential to detecting these unusual causes of abdominal pain.

Hiperfosfatasemia familiar: Reporte de un caso y consideraciones diagnósticas

Benign familial hyperphosphatasemia is a rare biochemical abnormality characterized by the presence of persistently elevated levels of serum alkaline phosphatase in several members of the same familiy, in the absence of disease or any known cause of hyperphosphatasemia. We describe one family affected with this biochemical abnormality and the epidemiology, genetic, isoenzymatic patterns and clinical significance of this entity are discussed.A 61-year-old man was referred to the Unit of Metabolic Bone Diseases for investigation of a lumbar pain with a history of urolithiasis and inguinofemoral hernia repair. The results of the physical examination and laboratory analysis were normal except for a high serum alkaline phosphatase level of 690 UI/l (reference range 40-129 UI/l). Isoenzymatic profile showed a 50% of intestinal variant, 33% of bone variant and 17% of liver variant isoenzymes. Skeletal radiographs and lumbar magnetic resonance imaging showed signs of osteoarthritis in the spine, bone scan showed a skeletal distribution of the radioisotope.One year later the biochemical exams showed similar raised levels of alkaline phosphatase. Family investigation revealed that one of the three sons of the patient had the same biochemical disorder.

Pediatric urolithiasis: an 8-year experience of single centre

The objective was to investigate the clinical features and metabolic and anatomic risk factors for kidney stone formation in our patient group. Between 1998 and 2005, 179 children (94 girls, 85 boys) followed in our department because of urolithiasis were enrolled to participate in our study. Clinical presentation, urinary tract infection, stone localisation, positive family history, stone composition, presence of anatomic abnormalities and urinary metabolic risk factors, and treatment modality were evaluated retrospectively. The mean age at diagnosis of stone disease was 4.5 years (range 0.25-15.3 years). The mean follow-up duration was 8 months (range 1-98). The major clinical presentations of our patients were abdominal pain and/or flank pain in 100 children (55.9%) and macroscopic hematuria in 25 (14%). Urinary tract infection was detected in 20% of patients on admission. Forty-three children (24%) had a urinary tract abnormality and ureteropelvic junction obstruction was the most common abnormality. A family history of stone disease was recorded in 98 patients (54.7%). Stones were located within the renal parenchyma in 90 patients. Hypercalciuria and hyperuricosuria were detected in 42.3 and 54.8% respectively. Stone analysis was performed in 63 children and calcium oxalate was a major mineral. Surgical treatment was performed in 49 children and extracorporeal shock wave lithotripsy (ESWL) in 41 children. We think that urolithiasis remains a serious problem in children in our country. Family history of urolithiasis, urologic abnormalities (especially under the age of 5 years), metabolic disorders and urinary tract infections tend to indicate childhood urolithiasis.

Aortic calcification in urolithiasis patients

To examine the relationship between urolithiasis and calcification of the aortic artery. We examined the relationship between urolithiasis and calcification of the aortic artery in 181 patients with urinary calcium stones (stone group) and in 181 without a history of urolithiasis (control group). All patients underwent abdominal CT to score the degree of calcification at the aortic arterial wall, as follows: 0, none; 1, <120 degrees calcification; 2, > or =120 degrees to <240 degrees calcification; and 3, > or =240 degrees calcification. Both the stone and control groups were further classified into three groups each according to gender and age. Aortic calcification scores differed significantly between the stone and control groups in males aged > or =20-<40 years (0.43+/-0.50 vs 0.13+/-0.35, respectively) and in females aged > or =60 years (1.81+/-0.74 vs 1.44+/-0.64, respectively). These findings suggest that common causative factors are associated with urolithiasis and arteriosclerosis and that adult males with arteriosclerosis develop urolithiasis more easily than those without.

Hypercalciuria in pediatric patients with ureteropelvic junction obstruction is of genetic origin

Genitourinary tract malformations are associated with urolithiasis. Hypercalciuria has been described in children with ureteropelvic junction obstruction (UPJO), although the etiology of this metabolic abnormality remains unknown. This study was conducted to find out whether children with UPJO have a higher prevalence of hypercalciuria and whether their family members are affected by hypercalciuria and/or urolithiasis. We studied the prevalence of hypercalciuria and urolithiasis in 27 children (14 males, 13 females) with UPJO and their parents. One patient had a history of renal colic, whereas imaging studies showed macroscopic renal lithiasis in two patients and calyceal microlithiasis in four. Hypercalciuria was found in 17/27 children (63%), 15 of whom (88%) had a familial history of urolithiasis: seven families in first-degree relatives, six in second-degree relatives and two in other relatives. Concerning the 10 children without hypercalciuria, seven of them (70%) had a family history of urolithiasis: four in first-degree relatives and three in second-degree relatives. The prevalences of both urolithiasis and hypercalciuria were not influenced by gender. Urolithiasis is associated with hypercalciuria in patients with UPJO. In accordance with previous data, our results show that the prevalence of hypercalciuria is greater in pediatric patients with UPJO than in the general population. Likewise, the prevalence of urolithiasis in the families of these children is also higher than that in the general population. Hypercalciuria was inherited as an autosomal dominant trait.

Prevalence of urolithiasis in rural Thebes, Greece

Worldwide, urolithiasis is the third most common urological disease affecting both males and females. Both genetic and environmental factors contribute to stone formation. The recurrence rate is approximately 50%, rising to 70% within 10 years and this condition represents a significant healthcare cost burden. An unusually frequent history of urolithiasis has been observed among patients from the rural area of Thebes, Viotia, Greece. To determine the prevalence of urolithiasis in Thebes. A representative sample of persons from the rural area of Thebes was questioned about the occurrence of urinary stones during their lifetime, and acute urolithiasis in 2005. A logistic regression model was used to contrast individuals with lithiasis to those without lithiasis. A total of 422 subjects participated in the study. We found a 15% prevalence of urolithiasis in the rural population of Thebes. The rate was slightly higher in men than in women in almost all age groups questioned, although this was not statistically significant. No case of urolithiasis was found in subjects under the age of 17 years. The prevalence of urolithiasis appeared to increase with age in both men and women. Those drinking bottled water were less likely to have lithiasis. The life time prevalence rate of urolithiasis observed in the rural area of Thebes was higher to that reported in other studies performed among males and females in the general population of Europe.

Características clínicas y de laboratorio en niños con nefrolitiasis: una serie de casos y controles

To evaluate the clinical and laboratory findings in pediatric patients with urolithiasis in a case control study and to obtain variables predicting a low risk of having urolithiasis. Retrospective analysis of 24 cases of children with urolithiasis (age range 3 to 17 years old) admitted to the pediatric emergency room or the hospital ward. Clinical and laboratory information was obtained from the clinical charts and compared with a control group of 29 patients with history of abdominal pain admitted to the hospital. Binary logistic regression and recursive partitioning analysis were used to obtain variables predicting a low risk of having urolithiasis. There was no difference in age, gender, dysuria or nausea (p > 0. 2) between groups. A difference regarding the presence of fever (p = 0.007), haematuria (p = 0.001), costovertebral angle tenderness (p = 0.004), family history (p = 0.007) and abdominal pain lasting more than 48 hs (p = 0.04) was detected. After logistic regression and using recursive partitioning, the presence or history of fever, absence of gross haematuria and no family history of urolithiasis showed a 100% negative predictive value and sensitivity (95% CI 84.7 to 100 and 89.2 to 100 respectively). Children with abdominal pain present a low risk of having urolithiasis if there is a history or presence of fever, absence of gross haematuria and a negative family history of urolithiasis in a first degree relative.

Nephrogenic Adenoma of the Urinary Bladder: Clinical Experience and Review of the Literature

Nephrogenic adenoma (NA) is a rare disease of the urinary tract. We report our clinical experience with this disease in the urinary bladder and review the literature. Between April 1994 and July 2004, 8 patients were diagnosed with NA of the urinary bladder: 3 men and 5 women, aged 23-77 years (mean 49.6). Multiple predisposing factors were analyzed. The mean follow-up time was 56 months. NA was not associated with transitional cell carcinoma in our series. All patients had recurrent urinary tract infection. Urinary tuberculosis was diagnosed in 2 patients. Two patients had undergone previous open urosurgery, and 4 patients had received previous endourologic management. A history of urolithiasis was found in 1 patient. Previous long-term urinary catheterization was noted in 3 patients. Two patients had received pelvic radiation therapy for cervical cancer. Urinary frequency and microscopic hematuria were found in all patients. All nephrogenic adenomas were treated with transurethral resection. Recurrent nephrogenic adenomas were diagnosed in 3 patients (median time to disease relapse, 7 months). Recurrent tumors were also treated with the endourologic method. NA is an uncommon benign metaplastic lesion occurring in the urothelium. Transurethral resection of NA provides a definite diagnosis and relief of symptoms. The recurrence rate of NA is relatively high, so careful and long-term follow-up is necessary.

Proposed Pathogenesis of Idiopathic Loin Pain–Hematuria Syndrome

To study loin pain-hematuria syndrome (LPHS) pathogenesis, we evaluated 43 consecutive patients for whom urological evaluation failed to disclose the cause of their recurrent flank pain and hematuria. Each underwent percutaneous kidney biopsy. In 9 patients, the biopsy specimen showed immunoglobulin A nephritis, an established cause of LPHS. We suggest these cases be designated secondary LPHS. They are not included in this analysis. The remaining patients (N = 34) are designated idiopathic (primary) LPHS. They are the basis of this report. Demographics of patients with primary LPHS are mean age of 30.8 +/- 10.3 years; 74% women; 94% white; and history of kidney stones, 47%, although none was obstructing. Primary LPHS kidney biopsy specimens showed red blood cells (RBCs) in multiple tubules, consistent with glomerular hematuria. Glomeruli were normal by means of light and immunofluorescent microscopy; however, more than 50% of biopsy specimens showed unusually thin or thick glomerular basement membranes. To assess whether the biopsy itself caused RBCs in tubules, we compared RBCs in renal tubular cross-sections from primary LPHS biopsies with those of normal kidneys (donors, n = 10). The mean percentage of tubular cross-sections containing RBCs was greater in primary LPHS than normal specimens (7.2% +/- 6.5% versus 1.6% +/- 1.0% [SD]; P < 0.0001), confirming glomerular hematuria in patients with primary LPHS. Primary LPHS pathogenesis includes glomerular hematuria, apparently from structurally abnormal glomerular basement membrane. Primary LPHS pain may be initiated by obstructing RBC casts and perhaps microcrystals in those with a history of urolithiasis. Nevertheless, other factors are needed to explain the severe pain in patients with primary LPHS.

Prevalence of urolithiasis in the autonomous city of Buenos Aires, Argentina

Urolithiasis is the third most common pathological disease afflicting the urinary tract, and usually occurs between the third and fourth decades of an individual's life. Epidemiological studies about this condition are lacking in our country. In 1998, we performed an epidemiological, cross-sectional study of the prevalence of urolithiasis in a sample of 1,086 subjects, which included men and women of all ages, selected from the general population of the city of Buenos Aires. The method used to gather basic information was an auto administered questionnaire about the present or past history of urolithiasis that was handled at the dwelling by a trained volunteer. We found a 3.96% lifetime prevalence of urolithiasis in the general population of Buenos Aires. The rate was slightly higher in men (4.35%) than in women (3.62%), with a male to female ratio of 1.19:1. No case of urolithiasis was found in subjects under the age of 20. In subjects over 19 years, the prevalence rate of the disease was 5.14%; 5.98% for men (CI 3.41-8.55%) and 4.49% for women (CI 2.61-6.37%). Prevalence increased with age, ranging from 2.75% in the 20-39 age group to 7.79% in those >or=60 years. The life time prevalence rate of urolithiasis observed in Buenos Aires is similar to that reported in a few other studies performed among males and females in the general population of USA and Europe. Prevalence of urolithiasis increases with age both in men and in women.

Granulomatous pyelitis associated with urinary obstruction: a comprehensive clinicopathologic study

Urinary obstruction is rarely associated with a distinct granulomatous inflammation, which involves the pyelocalyceal system and closely simulates infectious conditions including tuberculosis. Its clinicopathologic features, however, have not been adequately studied since there are only seven isolated reported cases. In a comprehensive study of 112 kidney specimens with urinary obstruction, we identified five cases of granulomatous pyelitis. The features of these cases were detailed and compared with the previously reported cases. Among the five identified subjects, three patients had history of urolithiasis and two had ureteral stenosis and all had stent placement 7 weeks to 12 years before nephrectomy for relief of the unilateral urinary obstruction. The age distribution was between 38 and 81 years. Two had end-stage renal disease or chronic renal failure. The pyelocaliceal system showed frank hydronephrosis (1 case) or partial dilatation (4 cases) and contained cheesy and gritty material in its lumen. Each case showed severe granulomatous inflammation, which was limited to the pelvic wall and closely associated with calcified debris, necrotic inflammatory cells, and material consistent with Tamm–Horsfall protein. The kidney showed chronic tubulointerstitial nephritis but without granulomas. Cultures of urine, blood, and the renal pelvic content, and special stains of tissue sections did not show fungi or mycobacteria in any case. Many of these features were also observed in previously reported cases. Granulomatous pyelitis is a rare but distinct cliniocopathologic entity characterized by severe noninfectious granulomatous inflammation limited to the renal pelvis, which is uniformely asociated with urinary obstruction and pyelocalyceal dilatation and may develop in response to accumulated calcified material in the renal pelvis. Awareness of this entity and its characteristic clinicopathologic features also helps eliminate an infectious etiology with obvious treatment and prognostic implications.

E-Cadherin Gene 3′-UTR C/T Polymorphism Is Associated with Prostate Cancer

Introduction: E-cadherin (CDH-1) is a cell-cell adhesive molecule which maintains cell integrity and communication between the intracellular and extracellular world. CDH-1 may therefore be related to carcinogenesis. A polymorphism located at the 3′-UTR of the CDH-1 gene is associated with stone disease; however, its relationship to prostate cancer has not been reported. We aimed to study whether there is an association between the 3′-UTR polymorphism and prostate cancer. Materials and Methods: We collected 96 patients with prostate cancer and 114 normal controls for this study. The polymorphism of the CDH-1 gene was studied by polymerase chain reaction-based restriction analysis. Results:There was a significant difference in genotype distribution of the CDH-1 gene polymorphism between cancer patients and normal controls (p < 0.001). The distribution of the CDH-1 gene CC genotype in prostate cancer patients (51.0%) was higher than in the controls (10.5%). The odds ratio for the CDH-1 ‘C’ allele was 2.896 (95% CI = 1.908–4.396). There was no significant difference according to age, pathological grading, clinical staging, and responsiveness to hormonal therapy among patients. Only 3 patients (3.1%) had a history of urolithiasis. Conclusions:The CDH-1 gene 3′-UTR C/T polymorphism is associated with prostate cancer. The ‘CC’ homozygote indicates a relatively higher risk for developing prostate cancer than other genotypes.

Influence of estrus status on urinary chemical parameters related to urolithiasis

The present study examines the urinary chemical parameters related to urolithiasis in healthy female volunteers during premenopause and menopause, and discusses the role of menopause in stone formation. We investigated 24-h urine parameters associated with urinary stones and focused upon estrus status. Participants comprised 30 healthy women, 15 childless, premenopausal women and 15 menopausal women without a history of urolithiasis. Our results showed that menopausal women have lower citrate and higher calcium excretion, which might enhance calcium stone crystallization. We propose that the estrus status of female patients should be considered when evaluating metabolic abnormalities.

DIAGNOSIS OF PEDIATRIC UROLITHIASIS: ROLE OF ULTRASOUND AND COMPUTERIZED TOMOGRAPHY

Pediatric urolithiasis is believed to be uncommon, and may present without the classic symptoms of renal colic. The objectives of this study were to describe the presenting features and radiographic evaluation of pediatric urolithiasis, and to determine the accuracy of ultrasound and unenhanced computerized tomography (CT) in detecting urolithiasis. We retrospectively reviewed the charts of children 0 to 18 years old with urolithiasis. Data collected included age, sex, race, presenting symptoms, radiographic studies performed during initial evaluation, calculus location and family history of urolithiasis. A total of 75 patients had complete data for analysis. Of these patients 54 (72%) had urolithiasis symptoms (flank pain, gross hematuria or both). Patients with urolithiasis symptoms were older at diagnosis (median age 11.9 years vs 1.0 years, p <0.001) and were more likely to have a family history of urolithiasis (54% vs 14%, p = 0.002). The 39 CTs performed were accurate in detecting calculi in children with urolithiasis symptoms (96% to 100%) and in those without symptoms (100%). The 36 ultrasounds performed had more variable accuracy in children with urolithiasis symptoms (33% to 100%) vs those without symptoms (89%). Ultrasound failed to detect urolithiasis in 41% of the patients with urolithiasis symptoms, compared to 5% with CT. CT was also highly accurate regardless of calculus location (89% to 100%), whereas ultrasound was again more variable (kidney 90%, kidney and ureter 75%, ureter alone 38%). Ultrasound failed to detect calculi in 41% of the children with urolithiasis symptoms, whereas CT was highly accurate in all situations. Unenhanced CT should be performed in all children with persistent urolithiasis symptoms and nondiagnostic ultrasound.

Outcomes of Shockwave Lithotripsy for Upper Urinary-Tract Stones: A Large-Scale Study at a Single Institution

We investigated the risk factors having an impact on the achievement of stone-free status and on the success rate, as well as on the likelihood of recurrence, in patients undergoing shockwave lithotripsy. We evaluated the characteristics and outcomes of 3023 patients (3254 renal units) with upper urinary-tract stones who underwent SWL at the Funabashi Clinic over a 13-year period. We assessed the stone-free and success rates for 2844 patients (3061 renal units) 3 months post-SWL. We also determined the recurrence rate for the 1078 patients (1139 renal units) who had achieved stone-free status at that time. Overall, stone-free status was achieved in 65.1% of patients, and the success rate was 85.7%. There were significant differences in the stone-free rates depending on patient age, history of urolithiasis, and presence of pyuria before SWL, as well as the number, location, size, and composition of the stones. Stones recurred in 326 of 1139 renal units (28.6%) during a mean follow-up of 36 months. The recurrence rates were 7.5%, 24.1%, and 33.0% after 1, 3, 5 years, respectively. Multiple stones, a history of urolithiasis, and stones located in the kidney or both kidneys plus the ureter significantly influenced recurrence. Multivariate analysis demonstrated that multiple stones were most significantly related to recurrence. Treatment with SWL has a low morbidity and high effectiveness. The number and location of stones and a history of urolithiasis significantly influence recurrence. Further studies of prophylactic therapy are required, especially for patients with these factors.

Clinical features determining the fate of a long-term, indwelling, forgotten double J stents

We review our experiences with forgotten stents and investigate the potential factors determining the degree of encrustation. Our series consists of nine cases of forgotten stent that had remained indwelling for more than 1 year (mean 36.1 months). We describe and compare their various clinical parameters in terms of encrustation. In addition, we briefly summarize our management schemes. All patients showed few stent related irritative symptoms. Six cases showing minimal or no encrustation shared the common feature of urine hypotonicity. Cystoscopic pullout was possible in these cases. The remaining three cases showed moderate to severe encrustation around the stent which required multiple procedures. Pyuria was observed in all cases and two patients had a history of urolithiasis. Finally, all cases were rendered stent and stone free. The fate of forgotten stents was dependent on the amount of encrustation around the stent. In our study, lithogenic history and presence of pyuria were associated with moderate to severe encrustation. Interestingly, patients showing urine hypotonicity tended to have a minimal encrustation on their stents and the stents were easily removed. Therefore, in patients with an impaired renal concentrating ability and a poor medical condition, the duration of indwelling stents might be safely prolonged if the patient has no risk factor for encrustation. As patients with forgotten stents are less likely to complain of stent related symptoms, thorough education of patients is important to prevent stent related complications.

Drug-Induced Renal Calculi

Drug-induced calculi represent 1-2% of all renal calculi. The drugs reported to produce calculi formation may be divided into two groups. The first one includes poorly soluble drugs with high urine excretion that favours crystallisation in the urine. Among poorly soluble molecules, triamterene was the leading cause of drug-containing urinary calculi in the 1970s, and it is still currently responsible for a significant number of calculi. In the last decade, drugs used for the treatment of HIV-infected patients, namely indinavir and sulfadiazine, have become the most frequent cause of drug-containing urinary calculi. Besides these drugs, about twenty other molecules may induce nephrolithiasis in patients receiving long-term treatment or high doses. Calculi analysis by physical methods, including infrared spectroscopy or x-ray diffraction, is needed to demonstrate the presence of the drug or its metabolites within the calculi. The second group includes drugs that provoke urinary calculi as a consequence of their metabolic effects. Here, diagnosis relies on careful clinical inquiry because physical methods are ineffective to differentiate between urinary calculi induced by the metabolic effects of a drug and common metabolic calculi. The incidence of such calculi, especially those resulting from calcium/vitamin D supplementation, is probably underestimated. Although drug-induced urinary calculi most often complicate high-dose, long-duration drug treatments, there also exist specific patient risk factors in relation to urine pH, urine output and other parameters, which provide a basis for preventive or curative treatment of calculi. Better awareness of the possible occurrence of lithogenic complications, preventive measures based on drug solubility characteristics and close surveillance of patients on long-term treatment with drugs with lithogenic potential, especially those with a history of urolithiasis, should reduce the incidence of drug-induced nephrolithiasis.

Levels of retinol and retinyl esters in plasma and urine of dogs with urolithiasis.

Vitamin A (VA) deficiency and Tamm-Horsfall glycoprotein (THP), a protein that binds retinol and retinyl esters in canine urine, might be involved in the pathogenesis of urolithiasis in dogs. In the present study, we assessed levels of retinol, retinyl esters, retinol-binding protein (RBP) and THP in plasma and urine of dogs with a history of urolithiasis (n = 25) compared with clinically healthy controls (n = 18). Plasma retinol concentrations were higher in dogs with uroliths of struvit (P < 0.01), calcium oxalate (P < 0.05), urate (P < 0.01) and cysteine, but there were no differences in the concentrations of plasma RBP and retinyl esters. Excretion of urinary retinol and retinyl esters were tentatively, but not significantly higher in the stone-forming groups, which was accompanied by increased levels of urinary RBP (P < 0.01) and lower excretions in THP (P < 0.01). The results show that VA deficiency may be excluded as a potential cause for canine urolithiasis. However, the occurrence of RBP and a concomitant reduction of THP in urine indicates a disturbed kidney function as cause or consequence of stone formation in dogs.

Urinary NAG in children with urolithiasis, nephrocalcinosis, or risk of urolithiasis.

A crucial role for cell-crystal interactions in the development of urolithiasis (UL) and nephrocalcinosis (NC) was previously observed in experiments with different cell lines mimicking renal epithelial cells. It was found that such cell-crystal interactions lead to tubular damage and/or or dysfunction. To find further proof for these observations, we measured the urinary N-acetyl-beta- d-glucosaminidase (NAG) excretion, a marker of proximal tubular damage, in children with UL or NC and in children with an increased risk of UL. We enrolled 142 children aged 4-16 years (mean 9.67+/-3.40 years), with 50 children having UL, 30 children with a history of UL (ULH), 20 patients with NC, 34 children with secondary hyperoxaluria (HyOx), and 8 children with idiopathic hypercalciuria (HC). Normal urinary NAG/Cr values were determined in a group of 70 healthy children aged 4-16 years (mean 10.06+/-3.97 years). The urinary NAG activity was measured using a colorimetric method and the results were expressed as molar creatinine (Cr) ratios. The highest median NAG/Cr ratios were found in children with UL plus hematuria (0.72 U/mM) and in children with UL (0.67 U/mM) or NC (0.48 U/mM), which were all significantly higher than those in controls (0.28 U/mmol, P<0.001 and P<0.05). The NAG/Cr ratios were increased above the upper normal reference interval of 0.63 U/mM (95th percentile) in 28 of 50 (56%) children with UL and in 9 of 20 (45%) children with NC. Although the ULH group also had significantly higher median NAG/Cr ratios (0.36 U/mM) compared with controls, the NAG/Cr ratio was only elevated in 4 of 30 (13%) patients. NAG values in children with secondary HyOx or HC were not different from controls. No correlation was found between the NAG/Cr ratios and the urinary excretion of oxalate or calcium. In conclusion, UL or NC may result in proximal tubular injury, which is rather the consequence of disease activity and of the mechanical influence of calculi, than of the metabolic background. The mechanism of cell damage in these conditions however, seems to be complex. Neither HyOx nor HC alone were sufficient to induce severe tubular damage expressed as an increase in NAG excretion in our patients.

Identifying Patients Who are Suitable for Stentless Ureteroscopy Following Treatment of Urolithiasis

Foregoing ureteral stents following ureteroscopy for urinary calculi is an evolving practice. Randomized trials support stent omission in select cases though generalizability is unclear and criteria for stentless ureteroscopy are unknown. Therefore, we sought to identify significant clinical characteristics affecting postoperative morbidity in unstented patients to provide a context for future randomized trials. Of 837 ureteroscopic procedures for urolithiasis performed at our institution from January 1997 through January 2002 a ureteral stent was not placed in 226 (32%). Among these patients 47 had no stone at the time of the procedure leaving 219 (26%) who were treated for urinary calculus disease. Multivariate logistic regression was used to determine the association of 24 variables with postoperative morbidity. Of the 219 patients treated with ureteroscopy 39 (18%) had a postoperative complication, which was obstructive in 26 (12%), infectious in 10 (5%), and related to patient co-morbidity in 3 (1%). Factors associated with postoperative morbidity included renal pelvic location (p = 0.02), lithotripsy (p = 0.03), bilateral procedure (p = 0.07), history of urolithiasis (p <0.0001), diabetes mellitus (p = 0.06), recent/recurrent infection (p <0.0001), operative time 45 minutes or greater (p = 0.07), operative time 45 minutes or greater plus lithotripsy (p = 0.0004), operative time 45 minutes or greater plus ureteral dilation (p = 0.07) and bilateral stentless procedure (p = 0.005). Multiple patient and operative factors may predispose a patient to postoperative morbidity after a stentless procedure. Future trials should prospectively validate the role of these factors in either promoting (e.g., history of urolithiasis) or preventing (e.g., preoperative stent) a postoperative complication in the setting of stentless ureteroscopy.