Ethnic background has minimal impact on the etiology of nephrolithiasis.

PURPOSE: Nephrolithiasis disproportionately affects white patients. However, recent studies propose an increase in the incidence of stone disease in nonwhite populations. We compared the metabolic risk factors of ethnically disparate stone formers from the same geographic region. MATERIALS AND METHODS: A retrospective review of 1,141 patients identified 98 (9%) nonwhite stone formers. Of these individuals 60 underwent a comprehensive metabolic evaluation, comprising 44 black, 8 Asian and 8 Hispanic patients. A similar sex and age matched group of 66 white stone forming patients were also identified for comparative analysis. Stone analyses were recorded when available. Urinary metabolic abnormalities were defined as low urine volume-urine volume less than 2,000 cc, gouty diathesis-pH 5.5 or less (normal level 5.5 to 6.5), hypercalciuria-calcium greater than 200 mg, hyperoxaluria-oxalate greater than 45 mg, hyperuricosuria-uric acid greater than 600 mg, hypocitraturia-citrate less than 600 mg and purine gluttony-sulfate greater than 20 mg. RESULTS: The incidence of metabolic abnormalities was surprisingly similar between the white and nonwhite stone formers. Whites have a higher prevalence of hypercalciuria compared with nonwhites (67% vs 25%, respectively, p <0.01). This comparison persisted when the white group was compared with individual ethnic groups (25% in each group). Whites also displayed a higher mean urinary calcium level (233 mg) than their nonwhite counterparts overall (146 mg), specifically with respect to blacks (146 mg, p <0.01). Asians had higher urine volumes with respect to whites and blacks (p <0.01) and, therefore, a decreased prevalence of low urine volumes (37.5% vs 74.2% and 79.5%, respectively). Hypocitraturia, hyperuricosuria, hyperoxaluria, gouty diathesis and high sulfate levels were equally represented among all ethnic groups. CONCLUSIONS: Although there appears to be a predominance of stone disease among whites, all racial groups demonstrated a remarkable similarity in the incidence of underlying metabolic abnormalities. These results suggest that dietary and environmental factors may be as important as ethnicity in the etiology of stone disease.

Ureteroscopic management of renal calculi in anomalous kidneys.

OBJECTIVES: To review our experience with ureteroscopy in treating patients with renal calculi in anomalous kidneys and to evaluate the efficacy of this approach. METHODS: Eight patients with renal calculi in anomalous kidneys who were managed by ureteroscopic procedures were identified. Demographic information, preoperative stone burden, operative information (ureteroscope size, lithotrite used, instruments used, duration of surgery, complications, stenting), follow-up imaging, and complications were obtained from the medical record. This information was analyzed to determine the most frequently used instruments and stone-free rates. RESULTS: Our cohort consisted of 4 patients with horseshoe kidneys (HSK) and 4 patients with pelvic kidneys (PK) (6 male, 2 female, mean age, 50.6 years). The average preoperative stone burden of the 11 treated calculi was 1.4 cm, with 5 stones located in the renal pelvis, 2 in the upper pole, and 4 in lower pole calyces. A 7.5F flexible ureteroscope, holmium laser lithotripsy, and nitinol baskets and graspers were used in all patients. Six patients had complete clearance of the stone on postoperative imaging (75% HSK, 75% PK), with 88% of patients asymptomatic after their procedure. No patients required additional surgical intervention. CONCLUSIONS: Flexible ureteroscopy with holmium laser lithotripsy and the use of nitinol baskets and graspers provides a reasonable alternative to shock wave lithotripsy in the management of patients harboring renal calculi in anomalous kidneys. In addition, ureteroscopy can be considered a primary option for managing select patients with symptomatic stones in PKs before a percutaneous surgical approach.

Effect of ureteral access sheath on stone-free rates in patients undergoing ureteroscopic management of renal calculi.

OBJECTIVES: To evaluate the effect of ureteral access sheaths (UASs) on stone-free rates (SFRs) during ureteroscopic treatment of renal calculi. Several advantages of UASs during flexible ureteroscopy have been documented. However, no study has evaluated their impact on SFRs. METHODS: We retrospectively reviewed all ureteroscopic cases for the management of renal stones performed at our Stone Center. Data were stratified according to the use or lack of use of the UAS. The groups were stratified by stone location within the kidney. Stone-free status was determined at 2 months postoperatively by either intravenous urography with tomograms or noncontrast renal computed tomography in patients with contrast allergies. RESULTS: A total of 256 ureteroscopic procedures for the removal of renal calculi were performed between 1997 and 2003 (173 with UAS and 83 without). The groups were similar in age, sex, and stone burden. Stents were placed in nearly 80% of patients. The lower renal pole represented the most common presenting location. Stone displacement with a ureteroscopic basket for efficient fragmentation was necessary in 34%. The overall SFR in the UAS group and non-UAS group was 79% and 67%, respectively (P = 0.042). The SFRs were improved for calculi in all portions of the kidney. CONCLUSIONS: In addition to facilitating ureteroscopic access, reducing costs, and lowering intrarenal pressures, the results of the current study suggest that UASs improve SFRs during the management of renal calculi. It is now our current practice to use the UAS routinely during ureteroscopic treatment of renal and upper ureteral calculi.

Metabolic risk factors and the impact of medical therapy on the management of nephrolithiasis in obese patients.

PURPOSE: Previous studies have demonstrated that obesity can increase the risk of stone formation as well as recurrence rates of stone disease. Yet appropriate medical management can significantly decrease the risk of recurrent stone disease. Therefore, we analyzed our obese patient population, assessing the risk factors for stone formation and the impact of selective medical therapy on recurrent stone formation. MATERIALS AND METHODS: A retrospective chart review was performed to identify obese patients with stone disease from our Stone Center. Metabolic risk factors for stones were identified as well as patient response to medical therapy. A similar analysis was performed on a group of age and sex matched nonobese stone formers. RESULTS: Of 1,021 patients 140 (14%) were identified as obese (body mass index greater than 30). Of these patients complete metabolic evaluations were available in 83 with an average followup of 2.3 years. The most common presenting metabolic abnormalities among these obese patients included gouty diathesis (54%), hypocitraturia (54%) and hyperuricosuria (43%), which presented at levels that were significantly higher than those of the nonobese stone formers (p <0.05). Stone analysis was available in 32 obese patients with 63% having uric acid calculi. After initiating treatment with selective medical therapy obese and nonobese patients demonstrated normalization of metabolic abnormalities, resulting in an average decrease in new stone formation from 1.75 to 0.15 new stones formed per patient per year in both groups. CONCLUSIONS: Obesity, as a result of dietary indiscretion, probable purine gluttony and possible type II diabetes, appears to have a significant role in recurrent stone formation. Appropriate metabolic evaluation, institution of medical therapy and dietary recommendations to decrease animal protein intake can significantly improve the risk of recurrent stone formation in these often difficult to treat patients.

Hand assisted laparoscopic training for postgraduate urologists: the role of mentoring.

PURPOSE: Hand assisted laparoscopy (HAL) has recently been accepted as a safe alternative for nephrectomy. HAL courses have been offered at several institutions to train novice laparoscopic surgeons in this minimally invasive surgical procedure. Mentoring by a course instructor or an experienced laparoscopist provides assistance to surgeons with their initial operation. However, to our knowledge the impact of mentoring on the clinical practice of HAL is not known. Therefore, we evaluated the clinical practice patterns of urologists following a postgraduate HAL course, comparing course graduates who underwent subsequent mentoring with those who were not mentored. MATERIALS AND METHODS: A total of 71 urologists attended a postgraduate training course in HAL at our institution between March 2002 and October 2002. Graduates were given the opportunity for one of the instructors to travel to their home institution and mentor them during their initial case(s). Followup surveys were mailed to the graduates in March 2003 to evaluate their practice patterns. Responses from returned surveys were entered into a dedicated database and data analysis was performed. RESULTS: Of the 71 surveys mailed 56 were returned (79%). The majority of respondents (91%) described themselves as community based general urologists. Respondents were categorized into 1 of 2 groups, namely group 1-those who had mentoring by a course instructor (23.2%) or another experienced laparoscopist (30.4%) and group 2-those who were not mentored (46.4%). The majority of group 1 respondents (93%) reported that they were still performing laparoscopic procedures at 6 months of followup. However, only 44% of the surgeons in group 2 were performing laparoscopy at 6 months. The majority of surgeons in group 1 (72%) reported that their laparoscopic experience had been sufficient to maintain their expertise compared to only 42% in group 2. CONCLUSIONS: Mentoring provides a useful adjunct to postgraduate urological training and the integration of laparoscopic techniques into the community based practice of urology.