Nutrition and urinary calcium stone formation in northwestern India: a case control study

The nutrient intake of 69 stone formers (SFs) from three subsets of the local population (urban 22, rural tribal 22 and rural nontribal 25) and 69 age, sex, weight and socioeconomically matched control subjects (NSs) (urban 20, rural tribal 22 and rural nontribal 27) was studied. Simultaneously their timed 24-h urine samples collected over a similar period were analyzed. In general caloric and protein intake was low in all the groups but was strikingly low in the rural subjects. Intake of all nutrients was lowest in the tribal group. Although no difference was observed in diet between NSs and SFs in the same population subjects, SFs had higher urinary excretion of oxalic acid and calcium and lower excretion of citric acid and excreted more saturated urine. Notably magnesium intake was normal in both NSs and SFs, but mean excretion of magnesium was lower than normal in all the groups, suggesting its defective absorption. The influence of dietary intake of protein, carbohydrate, fat, fiber, calcium and oxalic acid on urinary excretion of calcium, oxalic acid, uric acid, inorganic phosphorus, magnesium and citric acid was examined using the chi-square test. No association was observed, thus suggesting that this low nutrient intake did not influence the lithogenic process. Thus, the overall observations suggest: (a) poor nutrition, (b) no effect of diet on urinary stone disease, (c) no difference in the nutrient intake between NSs and SFs and (d) a higher excretion of promoters and a lower excretion of inhibitors in SFs than in NSs.     

Laparoscopic pyeloplasty and flexible nephroscopy: simultaneous treatment of ureteropelvic junction obstruction and nephrolithiasis.

BACKGROUND AND OBJECTIVE: Ureteropelvic junction obstruction and concomitant calculus disease may coexist. Therapeutic controversy exists regarding their ideal management. We report our use of flexible nephroscopy during laparoscopic pyeloplasty for caliceal stone removal. METHODS: From August 1998 through May 2002, 50 laparoscopic pyeloplasties were performed. Seven patients had documented ureteropelvic junction obstruction and ipsilateral nephrolithiasis. Preoperative stone burden and location were assessed. After pyelotomy, a 16 Fr flexible endoscope was passed through the uppermost trocar under direct laparoscopic guidance into the collecting system. Stone extraction was performed with a 2.4 Fr Nitinol basket. Postoperative imaging was assessed. RESULTS: Complete stone-free status confirmed by postoperative imaging was achieved in 6 of 7 patients. The longest individual stone diameter ranged from 4 mm to 13 mm (mean, 10.3 mm), and an average of 2.5 stones per patient was removed (range, 1 to 4 stones). Neither intraoperative fluoroscopy nor lithotripsy was required. No intraoperative or delayed complications were noted during a mean follow-up of 8.5 months (range, 2 to 17 months). CONCLUSIONS: Laparoscopic pyeloplasty and concomitant flexible nephroscopy with basket extraction is a simple, attractive alternative for the simultaneous treatment of ureteropelvic junction obstruction presenting with coexisting nephrolithiasis. It appears more efficacious when the stone number is limited and diameters measure from 5 mm to 20 mm.     

International comparison of cost effectiveness of medical management strategies for nephrolithiasis

Although medical therapy is known to reduce the risk of kidney stone recurrence, the cost effectiveness of medical prophylaxis is controversial. We evaluated medical treatment strategies including dietary measures (conservative), empiric medical therapy (empiric) or directed medical therapy (directed) based on comprehensive metabolic evaluation (CME) for patients with recurrent kidney stones, and compared the costs of these strategies using cost data from ten different countries. We previously established rates of stone formation in recurrent stone-formers, risk reduction of medical therapy, sensitivity of CME and rates of spontaneous stone passage from a comprehensive literature search (Lotan et al. 2004 J Urol 172: 2275). The costs of medication, surgical therapy, emergency room visits and CME for ten different countries were obtained from a published report of an international cost survey (Chandhoke 2002 J Urol 168: 937) as well as from our own county hospital in the US. Medication costs in the US were obtained from two national pharmacy chains. A decision tree model was created to compare the costs of different treatment strategies assuming cost accrual for metabolic evaluation, medical therapy and surgery or emergency room visits. For medical therapy, we assumed the distribution of medication use described in the published report, consisting of potassium citrate (60%), thiazide (30%) and allopurinol (10%). A nearly 20-fold difference in the costs of shock-wave lithotripsy, ureteroscopy and medication was found among different countries. From the model (US dollars/patient/year), conservative therapy alone was the most cost effective approach followed by empiric and directed medical therapy in all countries except in the UK. In the UK, the cost of drug therapy (estimated at $29/patient/year) resulted in empiric therapy being the most cost effective strategy for recurrent stone formers. The low likelihood of surgical intervention, as well as the low relative cost of surgery to medication, contributed to the higher cost of empiric and directed medical therapy strategies. Of note, despite the higher cost, drug treatment strategies were associated with significantly lower stone recurrence rates. We found that drug treatment strategies are more costly than conservative treatment but produce good control of stone formation. In all but one country (UK), dietary therapy was the most cost effective approach due to the relatively low cost of surgery compared with medication. The differential resource allocation to different components of a healthcare system (i.e. subsidized medication versus surgical treatment) in different countries determines the cost effectiveness of various treatment strategies.     

Development of upper tract stones in patients with congenital neurogenic bladder

ObjectivePatients with neurogenic bladder are at increased risk of developing upper tract stones. We hypothesized that patients with lower urinary tract stone disease are at greater risk of developing upper tract stones.MethodsWe performed a 10-year retrospective case–control study of patients with neurogenic bladder to determine the association between bladder and upper tract stones. Independent risk factors for upper tract stones were assessed. Cases and controls were matched 1:1. Univariable analysis was performed by Fisher's exact test and the Mann–Whitney U test. Multivariable logistic regression was performed.Results52 cases and controls were identified. Cases were significantly more likely to be non-ambulatory, have bowel–urinary tract interposition, thoracic level dysraphism, and history of bladder stones. On multivariable analysis, independent predictors of stone formation were male sex (OR 2.82; p = 0.02), dysraphism involving the thoracic spine (OR 3.37; p = 0.014) bowel–urinary tract interposition (OR 2.611; p = 0.038), and a history of bladder stones (OR 3.57; p = 0.015).ConclusionPatients with neurogenic bladder are at increased risk for upper tract stones. The presence of bladder stones may herald the development of upper tract stones. The predictors of stone disease identified should guide prospective studies to better understand the natural history of upper tract stone development in this population.     

Urinary neutrophil gelatinase–associated lipocalin,a biomarker for systemic inflammatory response syndrome in patients with nephrolithiasis

Background

The objective of this study was to determine the diagnostic value of neutrophil gelatinase–associated lipocalin (NGAL), C-reactive protein (CRP), and procalcitonin (PCT) in the prognosis of patients presenting with the systemic inflammatory response syndrome (SIRS) with nephrolithiasis.

Methods

Urine NGAL protein levels were measured by enzyme-linked immunosorbent assay in 87 patients presenting with nephrolithiasis who were diagnosed as SIRS. Additionally, 52 patients presenting with nephrolithiasis but without urinary tract infection and 30 healthy controls were also included in the study. Levels of serum CRP and PCT were also taken into consideration.

Results

Median urinary NGAL levels were significantly increased in the SIRS cohorts compared with nephrolithiasis without urinary tract infection patients (4.28 ng/mL versus 2.69 ng/mL, P < 0.001), and NGAL was markedly elevated even in the early stage of SIRS (3.23 ng/mL versus 2.69 ng/mL, P < 0.001). According to the receiver-operating characteristic analysis, NGAL demonstrated a high diagnostic value compared with either PCT or CRP. In the later stage of SIRS, NGAL remained a highly sensitive (76.8%) and specific (86.5%) diagnostic marker compared with either PCT or CRP. Moreover, the area under the curves of NGAL (0.822) were also superior to those seen in either PCT (0.657) or CRP (0.761).

Conclusion

Urinary NGAL is a highly sensitive and specific predictor of SIRS for patients presenting with nephrolithiasis. Further study of NGAL as a reliable biomarker of SIRS is required.     

High perirenal fat thickness predicts a greater risk of recurrence in Chinese patients with unilateral nephrolithiasis

IntroductionThe aim of this study was to evaluate the association between recurrence-free survival (RFS) and perirenal fat thickness (PFT) in a cohort of Chinese population with unilateral nephrolithiasis.MethodsWe retrospectively reviewed the medical records of 81 patients with unilateral nephrolithiasis in our center from January 2019 to June 2019. PFT measured on computed tomography (CT) scans was evaluated. Kaplan-Meier curves and log-rank tests were used to assess significant differences in RSF between high-PFT and low-PFT groups within sexes. Univariable and multivariable Cox regression analyses were used to evaluate the potential risk factors for renal stone recurrence.ResultsHigh PFT was significantly associated with high BMI and hyperlipidemia (p = .003 and.047, respectively). The PFT of stone-bearing kidney was significantly greater than PFT of non-stone-bearing kidney (0.77 ± 0.60 cm vs. 0.67 ± 0.58 cm, p = .002) . During the follow-up periods (median 31 months), 21 (25.9%) patients experienced ipsilateral renal stone recurrence. In addition, Kaplan–Meier survival curves showed that patients with low PFT had a significant better RFS than those with high PFT (p = .012). In the univariable Cox analyses, male sex and high PFT were significantly associated with a poor RFS (p = .042 and .018, respectively). Moreover, both male sex and high PFT retained significance in the multivariable analyses (p = .045 and .020, respectively).ConclusionsOur findings suggested that PFT is a noninvasive and feasible parameter, which may help in the risk stratification of renal stone recurrence in the follow-up periods.